diff --git a/orgize/src/elements/block.rs b/orgize/src/elements/block.rs
index a7a3eb8..fc0a011 100644
--- a/orgize/src/elements/block.rs
+++ b/orgize/src/elements/block.rs
@@ -1,6 +1,9 @@
 use std::borrow::Cow;
 
-use nom::{bytes::complete::tag_no_case, character::complete::alpha1, sequence::preceded, IResult};
+use nom::{
+    bytes::complete::tag_no_case, character::complete::alpha1, error::ParseError,
+    sequence::preceded, IResult,
+};
 
 use crate::parsers::{line, take_lines_while};
 
@@ -160,12 +163,20 @@ impl SourceBlock<'_> {
     // TODO: fn retain_labels() -> bool {  }
 }
 
-pub(crate) fn parse_block_element(input: &str) -> IResult<&str, (&str, Option<&str>, &str)> {
+#[inline]
+pub fn parse_block_element(input: &str) -> Option<(&str, (&str, Option<&str>, &str))> {
+    parse_block_element_internal::<()>(input).ok()
+}
+
+#[inline]
+fn parse_block_element_internal<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, (&'a str, Option<&'a str>, &'a str), E> {
     let (input, name) = preceded(tag_no_case("#+BEGIN_"), alpha1)(input)?;
     let (input, args) = line(input)?;
-    let end_line = format!(r"#+END_{}", name);
+    let end_line = format!("#+END_{}", name);
     let (input, contents) =
-        take_lines_while(|line| !line.trim().eq_ignore_ascii_case(&end_line))(input)?;
+        take_lines_while(|line| !line.trim().eq_ignore_ascii_case(&end_line))(input);
     let (input, _) = line(input)?;
 
     Ok((
@@ -184,22 +195,24 @@ pub(crate) fn parse_block_element(input: &str) -> IResult<&str, (&str, Option<&s
 
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        parse_block_element(
+        parse_block_element_internal::<VerboseError<&str>>(
             r#"#+BEGIN_SRC
 #+END_SRC"#
         ),
         Ok(("", ("SRC".into(), None, "")))
     );
     assert_eq!(
-        parse_block_element(
+        parse_block_element_internal::<VerboseError<&str>>(
             r#"#+begin_src
    #+end_src"#
         ),
         Ok(("", ("src".into(), None, "")))
     );
     assert_eq!(
-        parse_block_element(
+        parse_block_element_internal::<VerboseError<&str>>(
             r#"#+BEGIN_SRC javascript
 console.log('Hello World!');
 #+END_SRC
diff --git a/orgize/src/elements/clock.rs b/orgize/src/elements/clock.rs
index cb0f865..054bfee 100644
--- a/orgize/src/elements/clock.rs
+++ b/orgize/src/elements/clock.rs
@@ -4,11 +4,13 @@ use nom::{
     bytes::complete::tag,
     character::complete::{char, digit1, space0},
     combinator::recognize,
+    error::ParseError,
     sequence::separated_pair,
     IResult,
 };
 
-use crate::elements::{Datetime, Timestamp};
+use crate::elements::timestamp::{parse_inactive, Datetime, Timestamp};
+
 use crate::parsers::eol;
 
 /// Clock Element
@@ -42,54 +44,8 @@ pub enum Clock<'a> {
 }
 
 impl Clock<'_> {
-    pub(crate) fn parse(input: &str) -> IResult<&str, Clock<'_>> {
-        let (input, _) = tag("CLOCK:")(input)?;
-        let (input, _) = space0(input)?;
-        let (input, timestamp) = Timestamp::parse_inactive(input)?;
-
-        match timestamp {
-            Timestamp::InactiveRange {
-                start,
-                end,
-                repeater,
-                delay,
-            } => {
-                let (input, _) = space0(input)?;
-                let (input, _) = tag("=>")(input)?;
-                let (input, _) = space0(input)?;
-                let (input, duration) =
-                    recognize(separated_pair(digit1, char(':'), digit1))(input)?;
-                let (input, _) = eol(input)?;
-                Ok((
-                    input,
-                    Clock::Closed {
-                        start,
-                        end,
-                        repeater,
-                        delay,
-                        duration: duration.into(),
-                    },
-                ))
-            }
-            Timestamp::Inactive {
-                start,
-                repeater,
-                delay,
-            } => {
-                let (input, _) = eol(input)?;
-                Ok((
-                    input,
-                    Clock::Running {
-                        start,
-                        repeater,
-                        delay,
-                    },
-                ))
-            }
-            _ => unreachable!(
-                "`Timestamp::parse_inactive` only returns `Timestamp::InactiveRange` or `Timestamp::Inactive`."
-            ),
-        }
+    pub(crate) fn parse(input: &str) -> Option<(&str, Clock<'_>)> {
+        parse_clock::<()>(input).ok()
     }
 
     pub fn into_onwed(self) -> Clock<'static> {
@@ -171,10 +127,61 @@ impl Clock<'_> {
     }
 }
 
+fn parse_clock<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, Clock<'_>, E> {
+    let (input, _) = tag("CLOCK:")(input)?;
+    let (input, _) = space0(input)?;
+    let (input, timestamp) = parse_inactive(input)?;
+
+    match timestamp {
+        Timestamp::InactiveRange {
+            start,
+            end,
+            repeater,
+            delay,
+        } => {
+            let (input, _) = space0(input)?;
+            let (input, _) = tag("=>")(input)?;
+            let (input, _) = space0(input)?;
+            let (input, duration) = recognize(separated_pair(digit1, char(':'), digit1))(input)?;
+            let (input, _) = eol(input)?;
+            Ok((
+                input,
+                Clock::Closed {
+                    start,
+                    end,
+                    repeater,
+                    delay,
+                    duration: duration.into(),
+                },
+            ))
+        }
+        Timestamp::Inactive {
+            start,
+            repeater,
+            delay,
+        } => {
+            let (input, _) = eol(input)?;
+            Ok((
+                input,
+                Clock::Running {
+                    start,
+                    repeater,
+                    delay,
+                },
+            ))
+        }
+        _ => unreachable!(
+            "`parse_inactive` only returns `Timestamp::InactiveRange` or `Timestamp::Inactive`."
+        ),
+    }
+}
+
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        Clock::parse("CLOCK: [2003-09-16 Tue 09:39]"),
+        parse_clock::<VerboseError<&str>>("CLOCK: [2003-09-16 Tue 09:39]"),
         Ok((
             "",
             Clock::Running {
@@ -192,7 +199,9 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Clock::parse("CLOCK: [2003-09-16 Tue 09:39]--[2003-09-16 Tue 10:39] =>  1:00"),
+        parse_clock::<VerboseError<&str>>(
+            "CLOCK: [2003-09-16 Tue 09:39]--[2003-09-16 Tue 10:39] =>  1:00"
+        ),
         Ok((
             "",
             Clock::Closed {
diff --git a/orgize/src/elements/cookie.rs b/orgize/src/elements/cookie.rs
index 90a7d7b..6cb1ce0 100644
--- a/orgize/src/elements/cookie.rs
+++ b/orgize/src/elements/cookie.rs
@@ -5,6 +5,7 @@ use nom::{
     bytes::complete::tag,
     character::complete::digit0,
     combinator::recognize,
+    error::ParseError,
     sequence::{delimited, pair, separated_pair},
     IResult,
 };
@@ -19,23 +20,8 @@ pub struct Cookie<'a> {
 }
 
 impl Cookie<'_> {
-    #[inline]
-    pub(crate) fn parse(input: &str) -> IResult<&str, Cookie<'_>> {
-        let (input, value) = recognize(delimited(
-            tag("["),
-            alt((
-                separated_pair(digit0, tag("/"), digit0),
-                pair(digit0, tag("%")),
-            )),
-            tag("]"),
-        ))(input)?;
-
-        Ok((
-            input,
-            Cookie {
-                value: value.into(),
-            },
-        ))
+    pub(crate) fn parse(input: &str) -> Option<(&str, Cookie<'_>)> {
+        parse_cookie::<()>(input).ok()
     }
 
     pub fn into_owned(self) -> Cookie<'static> {
@@ -45,10 +31,31 @@ impl Cookie<'_> {
     }
 }
 
+#[inline]
+fn parse_cookie<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, Cookie<'a>, E> {
+    let (input, value) = recognize(delimited(
+        tag("["),
+        alt((
+            separated_pair(digit0, tag("/"), digit0),
+            pair(digit0, tag("%")),
+        )),
+        tag("]"),
+    ))(input)?;
+
+    Ok((
+        input,
+        Cookie {
+            value: value.into(),
+        },
+    ))
+}
+
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        Cookie::parse("[1/10]"),
+        parse_cookie::<VerboseError<&str>>("[1/10]"),
         Ok((
             "",
             Cookie {
@@ -57,7 +64,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Cookie::parse("[1/1000]"),
+        parse_cookie::<VerboseError<&str>>("[1/1000]"),
         Ok((
             "",
             Cookie {
@@ -66,7 +73,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Cookie::parse("[10%]"),
+        parse_cookie::<VerboseError<&str>>("[10%]"),
         Ok((
             "",
             Cookie {
@@ -75,7 +82,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Cookie::parse("[%]"),
+        parse_cookie::<VerboseError<&str>>("[%]"),
         Ok((
             "",
             Cookie {
@@ -84,7 +91,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Cookie::parse("[/]"),
+        parse_cookie::<VerboseError<&str>>("[/]"),
         Ok((
             "",
             Cookie {
@@ -93,7 +100,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Cookie::parse("[100/]"),
+        parse_cookie::<VerboseError<&str>>("[100/]"),
         Ok((
             "",
             Cookie {
@@ -102,7 +109,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Cookie::parse("[/100]"),
+        parse_cookie::<VerboseError<&str>>("[/100]"),
         Ok((
             "",
             Cookie {
@@ -111,8 +118,8 @@ fn parse() {
         ))
     );
 
-    assert!(Cookie::parse("[10% ]").is_err());
-    assert!(Cookie::parse("[1//100]").is_err());
-    assert!(Cookie::parse("[1\\100]").is_err());
-    assert!(Cookie::parse("[10%%]").is_err());
+    assert!(parse_cookie::<VerboseError<&str>>("[10% ]").is_err());
+    assert!(parse_cookie::<VerboseError<&str>>("[1//100]").is_err());
+    assert!(parse_cookie::<VerboseError<&str>>("[1\\100]").is_err());
+    assert!(parse_cookie::<VerboseError<&str>>("[10%%]").is_err());
 }
diff --git a/orgize/src/elements/drawer.rs b/orgize/src/elements/drawer.rs
index 5cb94a2..0a7b325 100644
--- a/orgize/src/elements/drawer.rs
+++ b/orgize/src/elements/drawer.rs
@@ -2,6 +2,7 @@ use std::borrow::Cow;
 
 use nom::{
     bytes::complete::{tag, take_while1},
+    error::ParseError,
     sequence::delimited,
     IResult,
 };
@@ -18,19 +19,8 @@ pub struct Drawer<'a> {
 }
 
 impl Drawer<'_> {
-    #[inline]
-    pub(crate) fn parse(input: &str) -> IResult<&str, (Drawer<'_>, &str)> {
-        let (input, name) = delimited(
-            tag(":"),
-            take_while1(|c: char| c.is_ascii_alphabetic() || c == '-' || c == '_'),
-            tag(":"),
-        )(input)?;
-        let (input, _) = eol(input)?;
-        let (input, contents) =
-            take_lines_while(|line| !line.trim().eq_ignore_ascii_case(":END:"))(input)?;
-        let (input, _) = line(input)?;
-
-        Ok((input, (Drawer { name: name.into() }, contents)))
+    pub(crate) fn parse(input: &str) -> Option<(&str, (Drawer<'_>, &str))> {
+        parse_drawer::<()>(input).ok()
     }
 
     pub fn into_owned(self) -> Drawer<'static> {
@@ -40,10 +30,29 @@ impl Drawer<'_> {
     }
 }
 
+#[inline]
+pub fn parse_drawer<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, (Drawer<'a>, &'a str), E> {
+    let (input, name) = delimited(
+        tag(":"),
+        take_while1(|c: char| c.is_ascii_alphabetic() || c == '-' || c == '_'),
+        tag(":"),
+    )(input)?;
+    let (input, _) = eol(input)?;
+    let (input, contents) =
+        take_lines_while(|line| !line.trim().eq_ignore_ascii_case(":END:"))(input);
+    let (input, _) = line(input)?;
+
+    Ok((input, (Drawer { name: name.into() }, contents)))
+}
+
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        Drawer::parse(":PROPERTIES:\n  :CUSTOM_ID: id\n  :END:"),
+        parse_drawer::<VerboseError<&str>>(":PROPERTIES:\n  :CUSTOM_ID: id\n  :END:"),
         Ok((
             "",
             (
diff --git a/orgize/src/elements/dyn_block.rs b/orgize/src/elements/dyn_block.rs
index 6a1050a..4afe1c3 100644
--- a/orgize/src/elements/dyn_block.rs
+++ b/orgize/src/elements/dyn_block.rs
@@ -3,6 +3,7 @@ use std::borrow::Cow;
 use nom::{
     bytes::complete::tag_no_case,
     character::complete::{alpha1, space1},
+    error::ParseError,
     IResult,
 };
 
@@ -21,30 +22,8 @@ pub struct DynBlock<'a> {
 }
 
 impl DynBlock<'_> {
-    #[inline]
-    pub(crate) fn parse(input: &str) -> IResult<&str, (DynBlock<'_>, &str)> {
-        let (input, _) = tag_no_case("#+BEGIN:")(input)?;
-        let (input, _) = space1(input)?;
-        let (input, name) = alpha1(input)?;
-        let (input, args) = line(input)?;
-        let (input, contents) =
-            take_lines_while(|line| !line.trim().eq_ignore_ascii_case("#+END:"))(input)?;
-        let (input, _) = line(input)?;
-
-        Ok((
-            input,
-            (
-                DynBlock {
-                    block_name: name.into(),
-                    arguments: if args.trim().is_empty() {
-                        None
-                    } else {
-                        Some(args.trim().into())
-                    },
-                },
-                contents,
-            ),
-        ))
+    pub(crate) fn parse(input: &str) -> Option<(&str, (DynBlock<'_>, &str))> {
+        parse_dyn_block::<()>(input).ok()
     }
 
     pub fn into_owned(self) -> DynBlock<'static> {
@@ -55,11 +34,41 @@ impl DynBlock<'_> {
     }
 }
 
+#[inline]
+fn parse_dyn_block<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, (DynBlock<'a>, &'a str), E> {
+    let (input, _) = tag_no_case("#+BEGIN:")(input)?;
+    let (input, _) = space1(input)?;
+    let (input, name) = alpha1(input)?;
+    let (input, args) = line(input)?;
+    let (input, contents) =
+        take_lines_while(|line| !line.trim().eq_ignore_ascii_case("#+END:"))(input);
+    let (input, _) = line(input)?;
+
+    Ok((
+        input,
+        (
+            DynBlock {
+                block_name: name.into(),
+                arguments: if args.trim().is_empty() {
+                    None
+                } else {
+                    Some(args.trim().into())
+                },
+            },
+            contents,
+        ),
+    ))
+}
+
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     // TODO: testing
     assert_eq!(
-        DynBlock::parse(
+        parse_dyn_block::<VerboseError<&str>>(
             r#"#+BEGIN: clocktable :scope file
 CONTENTS
 #+END:
diff --git a/orgize/src/elements/fn_def.rs b/orgize/src/elements/fn_def.rs
index b15fd2b..7a1934c 100644
--- a/orgize/src/elements/fn_def.rs
+++ b/orgize/src/elements/fn_def.rs
@@ -2,6 +2,7 @@ use std::borrow::Cow;
 
 use nom::{
     bytes::complete::{tag, take_while1},
+    error::ParseError,
     sequence::delimited,
     IResult,
 };
@@ -18,24 +19,8 @@ pub struct FnDef<'a> {
 }
 
 impl FnDef<'_> {
-    #[inline]
-    pub(crate) fn parse(input: &str) -> IResult<&str, (FnDef<'_>, &str)> {
-        let (input, label) = delimited(
-            tag("[fn:"),
-            take_while1(|c: char| c.is_ascii_alphanumeric() || c == '-' || c == '_'),
-            tag("]"),
-        )(input)?;
-        let (input, content) = line(input)?;
-
-        Ok((
-            input,
-            (
-                FnDef {
-                    label: label.into(),
-                },
-                content,
-            ),
-        ))
+    pub(crate) fn parse(input: &str) -> Option<(&str, (FnDef<'_>, &str))> {
+        parse_fn_def::<()>(input).ok()
     }
 
     pub fn into_owned(self) -> FnDef<'static> {
@@ -45,14 +30,38 @@ impl FnDef<'_> {
     }
 }
 
+#[inline]
+fn parse_fn_def<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, (FnDef<'a>, &'a str), E> {
+    let (input, label) = delimited(
+        tag("[fn:"),
+        take_while1(|c: char| c.is_ascii_alphanumeric() || c == '-' || c == '_'),
+        tag("]"),
+    )(input)?;
+    let (input, content) = line(input)?;
+
+    Ok((
+        input,
+        (
+            FnDef {
+                label: label.into(),
+            },
+            content,
+        ),
+    ))
+}
+
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        FnDef::parse("[fn:1] https://orgmode.org"),
+        parse_fn_def::<VerboseError<&str>>("[fn:1] https://orgmode.org"),
         Ok(("", (FnDef { label: "1".into() }, " https://orgmode.org")))
     );
     assert_eq!(
-        FnDef::parse("[fn:word_1] https://orgmode.org"),
+        parse_fn_def::<VerboseError<&str>>("[fn:word_1] https://orgmode.org"),
         Ok((
             "",
             (
@@ -64,7 +73,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        FnDef::parse("[fn:WORD-1] https://orgmode.org"),
+        parse_fn_def::<VerboseError<&str>>("[fn:WORD-1] https://orgmode.org"),
         Ok((
             "",
             (
@@ -76,7 +85,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        FnDef::parse("[fn:WORD]"),
+        parse_fn_def::<VerboseError<&str>>("[fn:WORD]"),
         Ok((
             "",
             (
@@ -88,7 +97,7 @@ fn parse() {
         ))
     );
 
-    assert!(FnDef::parse("[fn:] https://orgmode.org").is_err());
-    assert!(FnDef::parse("[fn:wor d] https://orgmode.org").is_err());
-    assert!(FnDef::parse("[fn:WORD https://orgmode.org").is_err());
+    assert!(parse_fn_def::<VerboseError<&str>>("[fn:] https://orgmode.org").is_err());
+    assert!(parse_fn_def::<VerboseError<&str>>("[fn:wor d] https://orgmode.org").is_err());
+    assert!(parse_fn_def::<VerboseError<&str>>("[fn:WORD https://orgmode.org").is_err());
 }
diff --git a/orgize/src/elements/fn_ref.rs b/orgize/src/elements/fn_ref.rs
index 770f403..87c5943 100644
--- a/orgize/src/elements/fn_ref.rs
+++ b/orgize/src/elements/fn_ref.rs
@@ -4,8 +4,7 @@ use memchr::memchr2_iter;
 use nom::{
     bytes::complete::{tag, take_while},
     combinator::opt,
-    error::ErrorKind,
-    error_position,
+    error::{ErrorKind, ParseError},
     sequence::preceded,
     Err, IResult,
 };
@@ -21,36 +20,9 @@ pub struct FnRef<'a> {
     pub definition: Option<Cow<'a, str>>,
 }
 
-fn balanced_brackets(input: &str) -> IResult<&str, &str> {
-    let mut pairs = 1;
-    for i in memchr2_iter(b'[', b']', input.as_bytes()) {
-        if input.as_bytes()[i] == b'[' {
-            pairs += 1;
-        } else if pairs != 1 {
-            pairs -= 1;
-        } else {
-            return Ok((&input[i..], &input[0..i]));
-        }
-    }
-    Err(Err::Error(error_position!(input, ErrorKind::Tag)))
-}
-
 impl FnRef<'_> {
-    #[inline]
-    pub(crate) fn parse(input: &str) -> IResult<&str, FnRef<'_>> {
-        let (input, _) = tag("[fn:")(input)?;
-        let (input, label) =
-            take_while(|c: char| c.is_ascii_alphanumeric() || c == '-' || c == '_')(input)?;
-        let (input, definition) = opt(preceded(tag(":"), balanced_brackets))(input)?;
-        let (input, _) = tag("]")(input)?;
-
-        Ok((
-            input,
-            FnRef {
-                label: label.into(),
-                definition: definition.map(Into::into),
-            },
-        ))
+    pub(crate) fn parse(input: &str) -> Option<(&str, FnRef<'_>)> {
+        parse_fn_ref::<()>(input).ok()
     }
 
     pub fn into_owned(self) -> FnRef<'static> {
@@ -61,10 +33,43 @@ impl FnRef<'_> {
     }
 }
 
+#[inline]
+fn parse_fn_ref<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, FnRef<'a>, E> {
+    let (input, _) = tag("[fn:")(input)?;
+    let (input, label) =
+        take_while(|c: char| c.is_ascii_alphanumeric() || c == '-' || c == '_')(input)?;
+    let (input, definition) = opt(preceded(tag(":"), balanced_brackets))(input)?;
+    let (input, _) = tag("]")(input)?;
+
+    Ok((
+        input,
+        FnRef {
+            label: label.into(),
+            definition: definition.map(Into::into),
+        },
+    ))
+}
+
+fn balanced_brackets<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, &'a str, E> {
+    let mut pairs = 1;
+    for i in memchr2_iter(b'[', b']', input.as_bytes()) {
+        if input.as_bytes()[i] == b'[' {
+            pairs += 1;
+        } else if pairs != 1 {
+            pairs -= 1;
+        } else {
+            return Ok((&input[i..], &input[0..i]));
+        }
+    }
+    Err(Err::Error(E::from_error_kind(input, ErrorKind::Tag)))
+}
+
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        FnRef::parse("[fn:1]"),
+        parse_fn_ref::<VerboseError<&str>>("[fn:1]"),
         Ok((
             "",
             FnRef {
@@ -74,7 +79,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        FnRef::parse("[fn:1:2]"),
+        parse_fn_ref::<VerboseError<&str>>("[fn:1:2]"),
         Ok((
             "",
             FnRef {
@@ -84,7 +89,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        FnRef::parse("[fn::2]"),
+        parse_fn_ref::<VerboseError<&str>>("[fn::2]"),
         Ok((
             "",
             FnRef {
@@ -94,7 +99,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        FnRef::parse("[fn::[]]"),
+        parse_fn_ref::<VerboseError<&str>>("[fn::[]]"),
         Ok((
             "",
             FnRef {
@@ -104,5 +109,5 @@ fn parse() {
         ))
     );
 
-    assert!(FnRef::parse("[fn::[]").is_err());
+    assert!(parse_fn_ref::<VerboseError<&str>>("[fn::[]").is_err());
 }
diff --git a/orgize/src/elements/inline_call.rs b/orgize/src/elements/inline_call.rs
index 22b67f5..a5f0ecc 100644
--- a/orgize/src/elements/inline_call.rs
+++ b/orgize/src/elements/inline_call.rs
@@ -3,6 +3,7 @@ use std::borrow::Cow;
 use nom::{
     bytes::complete::{tag, take_till},
     combinator::opt,
+    error::ParseError,
     sequence::{delimited, preceded},
     IResult,
 };
@@ -25,34 +26,8 @@ pub struct InlineCall<'a> {
 }
 
 impl InlineCall<'_> {
-    #[inline]
-    pub(crate) fn parse(input: &str) -> IResult<&str, InlineCall<'_>> {
-        let (input, name) = preceded(
-            tag("call_"),
-            take_till(|c| c == '[' || c == '\n' || c == '(' || c == ')'),
-        )(input)?;
-        let (input, inside_header) = opt(delimited(
-            tag("["),
-            take_till(|c| c == ']' || c == '\n'),
-            tag("]"),
-        ))(input)?;
-        let (input, arguments) =
-            delimited(tag("("), take_till(|c| c == ')' || c == '\n'), tag(")"))(input)?;
-        let (input, end_header) = opt(delimited(
-            tag("["),
-            take_till(|c| c == ']' || c == '\n'),
-            tag("]"),
-        ))(input)?;
-
-        Ok((
-            input,
-            InlineCall {
-                name: name.into(),
-                arguments: arguments.into(),
-                inside_header: inside_header.map(Into::into),
-                end_header: end_header.map(Into::into),
-            },
-        ))
+    pub(crate) fn parse(input: &str) -> Option<(&str, InlineCall<'_>)> {
+        parse_inline_call::<()>(input).ok()
     }
 
     pub fn into_owned(self) -> InlineCall<'static> {
@@ -65,10 +40,44 @@ impl InlineCall<'_> {
     }
 }
 
+#[inline]
+fn parse_inline_call<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, InlineCall<'a>, E> {
+    let (input, name) = preceded(
+        tag("call_"),
+        take_till(|c| c == '[' || c == '\n' || c == '(' || c == ')'),
+    )(input)?;
+    let (input, inside_header) = opt(delimited(
+        tag("["),
+        take_till(|c| c == ']' || c == '\n'),
+        tag("]"),
+    ))(input)?;
+    let (input, arguments) =
+        delimited(tag("("), take_till(|c| c == ')' || c == '\n'), tag(")"))(input)?;
+    let (input, end_header) = opt(delimited(
+        tag("["),
+        take_till(|c| c == ']' || c == '\n'),
+        tag("]"),
+    ))(input)?;
+
+    Ok((
+        input,
+        InlineCall {
+            name: name.into(),
+            arguments: arguments.into(),
+            inside_header: inside_header.map(Into::into),
+            end_header: end_header.map(Into::into),
+        },
+    ))
+}
+
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        InlineCall::parse("call_square(4)"),
+        parse_inline_call::<VerboseError<&str>>("call_square(4)"),
         Ok((
             "",
             InlineCall {
@@ -80,7 +89,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        InlineCall::parse("call_square[:results output](4)"),
+        parse_inline_call::<VerboseError<&str>>("call_square[:results output](4)"),
         Ok((
             "",
             InlineCall {
@@ -92,7 +101,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        InlineCall::parse("call_square(4)[:results html]"),
+        parse_inline_call::<VerboseError<&str>>("call_square(4)[:results html]"),
         Ok((
             "",
             InlineCall {
@@ -104,7 +113,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        InlineCall::parse("call_square[:results output](4)[:results html]"),
+        parse_inline_call::<VerboseError<&str>>("call_square[:results output](4)[:results html]"),
         Ok((
             "",
             InlineCall {
diff --git a/orgize/src/elements/inline_src.rs b/orgize/src/elements/inline_src.rs
index cb571a5..d03faa8 100644
--- a/orgize/src/elements/inline_src.rs
+++ b/orgize/src/elements/inline_src.rs
@@ -3,6 +3,7 @@ use std::borrow::Cow;
 use nom::{
     bytes::complete::{tag, take_till, take_while1},
     combinator::opt,
+    error::ParseError,
     sequence::delimited,
     IResult,
 };
@@ -22,27 +23,8 @@ pub struct InlineSrc<'a> {
 }
 
 impl InlineSrc<'_> {
-    #[inline]
-    pub(crate) fn parse(input: &str) -> IResult<&str, InlineSrc<'_>> {
-        let (input, _) = tag("src_")(input)?;
-        let (input, lang) =
-            take_while1(|c: char| !c.is_ascii_whitespace() && c != '[' && c != '{')(input)?;
-        let (input, options) = opt(delimited(
-            tag("["),
-            take_till(|c| c == '\n' || c == ']'),
-            tag("]"),
-        ))(input)?;
-        let (input, body) =
-            delimited(tag("{"), take_till(|c| c == '\n' || c == '}'), tag("}"))(input)?;
-
-        Ok((
-            input,
-            InlineSrc {
-                lang: lang.into(),
-                options: options.map(Into::into),
-                body: body.into(),
-            },
-        ))
+    pub(crate) fn parse(input: &str) -> Option<(&str, InlineSrc<'_>)> {
+        parse_inline_src::<()>(input).ok()
     }
 
     pub fn into_owned(self) -> InlineSrc<'static> {
@@ -54,10 +36,36 @@ impl InlineSrc<'_> {
     }
 }
 
+#[inline]
+fn parse_inline_src<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, InlineSrc<'a>, E> {
+    let (input, _) = tag("src_")(input)?;
+    let (input, lang) =
+        take_while1(|c: char| !c.is_ascii_whitespace() && c != '[' && c != '{')(input)?;
+    let (input, options) = opt(delimited(
+        tag("["),
+        take_till(|c| c == '\n' || c == ']'),
+        tag("]"),
+    ))(input)?;
+    let (input, body) = delimited(tag("{"), take_till(|c| c == '\n' || c == '}'), tag("}"))(input)?;
+
+    Ok((
+        input,
+        InlineSrc {
+            lang: lang.into(),
+            options: options.map(Into::into),
+            body: body.into(),
+        },
+    ))
+}
+
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        InlineSrc::parse("src_C{int a = 0;}"),
+        parse_inline_src::<VerboseError<&str>>("src_C{int a = 0;}"),
         Ok((
             "",
             InlineSrc {
@@ -68,7 +76,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        InlineSrc::parse("src_xml[:exports code]{<tag>text</tag>}"),
+        parse_inline_src::<VerboseError<&str>>("src_xml[:exports code]{<tag>text</tag>}"),
         Ok((
             "",
             InlineSrc {
@@ -79,7 +87,11 @@ fn parse() {
         ))
     );
 
-    assert!(InlineSrc::parse("src_xml[:exports code]{<tag>text</tag>").is_err());
-    assert!(InlineSrc::parse("src_[:exports code]{<tag>text</tag>}").is_err());
-    assert!(InlineSrc::parse("src_xml[:exports code]").is_err());
+    assert!(
+        parse_inline_src::<VerboseError<&str>>("src_xml[:exports code]{<tag>text</tag>").is_err()
+    );
+    assert!(
+        parse_inline_src::<VerboseError<&str>>("src_[:exports code]{<tag>text</tag>}").is_err()
+    );
+    assert!(parse_inline_src::<VerboseError<&str>>("src_xml[:exports code]").is_err());
 }
diff --git a/orgize/src/elements/keyword.rs b/orgize/src/elements/keyword.rs
index 0f367d1..0625284 100644
--- a/orgize/src/elements/keyword.rs
+++ b/orgize/src/elements/keyword.rs
@@ -3,6 +3,7 @@ use std::borrow::Cow;
 use nom::{
     bytes::complete::{tag, take_till},
     combinator::opt,
+    error::ParseError,
     sequence::delimited,
     IResult,
 };
@@ -48,7 +49,15 @@ impl BabelCall<'_> {
     }
 }
 
-pub(crate) fn parse_keyword(input: &str) -> IResult<&str, (&str, Option<&str>, &str)> {
+#[inline]
+pub fn parse_keyword(input: &str) -> Option<(&str, (&str, Option<&str>, &str))> {
+    parse_keyword_internal::<()>(input).ok()
+}
+
+#[inline]
+fn parse_keyword_internal<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, (&'a str, Option<&'a str>, &'a str), E> {
     let (input, _) = tag("#+")(input)?;
     let (input, key) = take_till(|c: char| c.is_ascii_whitespace() || c == ':' || c == '[')(input)?;
     let (input, optional) = opt(delimited(
@@ -64,36 +73,44 @@ pub(crate) fn parse_keyword(input: &str) -> IResult<&str, (&str, Option<&str>, &
 
 #[test]
 fn parse() {
-    assert_eq!(parse_keyword("#+KEY:"), Ok(("", ("KEY", None, ""))));
+    use nom::error::VerboseError;
+
     assert_eq!(
-        parse_keyword("#+KEY: VALUE"),
+        parse_keyword_internal::<VerboseError<&str>>("#+KEY:"),
+        Ok(("", ("KEY", None, "")))
+    );
+    assert_eq!(
+        parse_keyword_internal::<VerboseError<&str>>("#+KEY: VALUE"),
         Ok(("", ("KEY", None, "VALUE")))
     );
     assert_eq!(
-        parse_keyword("#+K_E_Y: VALUE"),
+        parse_keyword_internal::<VerboseError<&str>>("#+K_E_Y: VALUE"),
         Ok(("", ("K_E_Y", None, "VALUE")))
     );
     assert_eq!(
-        parse_keyword("#+KEY:VALUE\n"),
+        parse_keyword_internal::<VerboseError<&str>>("#+KEY:VALUE\n"),
         Ok(("", ("KEY", None, "VALUE")))
     );
-    assert!(parse_keyword("#+KE Y: VALUE").is_err());
-    assert!(parse_keyword("#+ KEY: VALUE").is_err());
-
-    assert_eq!(parse_keyword("#+RESULTS:"), Ok(("", ("RESULTS", None, ""))));
+    assert!(parse_keyword_internal::<VerboseError<&str>>("#+KE Y: VALUE").is_err());
+    assert!(parse_keyword_internal::<VerboseError<&str>>("#+ KEY: VALUE").is_err());
 
     assert_eq!(
-        parse_keyword("#+ATTR_LATEX: :width 5cm\n"),
+        parse_keyword_internal::<VerboseError<&str>>("#+RESULTS:"),
+        Ok(("", ("RESULTS", None, "")))
+    );
+
+    assert_eq!(
+        parse_keyword_internal::<VerboseError<&str>>("#+ATTR_LATEX: :width 5cm\n"),
         Ok(("", ("ATTR_LATEX", None, ":width 5cm")))
     );
 
     assert_eq!(
-        parse_keyword("#+CALL: double(n=4)"),
+        parse_keyword_internal::<VerboseError<&str>>("#+CALL: double(n=4)"),
         Ok(("", ("CALL", None, "double(n=4)")))
     );
 
     assert_eq!(
-        parse_keyword("#+CAPTION[Short caption]: Longer caption."),
+        parse_keyword_internal::<VerboseError<&str>>("#+CAPTION[Short caption]: Longer caption."),
         Ok(("", ("CAPTION", Some("Short caption"), "Longer caption.",)))
     );
 }
diff --git a/orgize/src/elements/link.rs b/orgize/src/elements/link.rs
index 15292ef..34b3b5b 100644
--- a/orgize/src/elements/link.rs
+++ b/orgize/src/elements/link.rs
@@ -3,6 +3,7 @@ use std::borrow::Cow;
 use nom::{
     bytes::complete::{tag, take_while},
     combinator::opt,
+    error::ParseError,
     sequence::delimited,
     IResult,
 };
@@ -20,25 +21,8 @@ pub struct Link<'a> {
 
 impl Link<'_> {
     #[inline]
-    pub(crate) fn parse(input: &str) -> IResult<&str, Link<'_>> {
-        let (input, path) = delimited(
-            tag("[["),
-            take_while(|c: char| c != '<' && c != '>' && c != '\n' && c != ']'),
-            tag("]"),
-        )(input)?;
-        let (input, desc) = opt(delimited(
-            tag("["),
-            take_while(|c: char| c != '[' && c != ']'),
-            tag("]"),
-        ))(input)?;
-        let (input, _) = tag("]")(input)?;
-        Ok((
-            input,
-            Link {
-                path: path.into(),
-                desc: desc.map(Into::into),
-            },
-        ))
+    pub(crate) fn parse(input: &str) -> Option<(&str, Link<'_>)> {
+        parse_link::<()>(input).ok()
     }
 
     pub fn into_owned(self) -> Link<'static> {
@@ -49,10 +33,34 @@ impl Link<'_> {
     }
 }
 
+#[inline]
+fn parse_link<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, Link<'a>, E> {
+    let (input, path) = delimited(
+        tag("[["),
+        take_while(|c: char| c != '<' && c != '>' && c != '\n' && c != ']'),
+        tag("]"),
+    )(input)?;
+    let (input, desc) = opt(delimited(
+        tag("["),
+        take_while(|c: char| c != '[' && c != ']'),
+        tag("]"),
+    ))(input)?;
+    let (input, _) = tag("]")(input)?;
+    Ok((
+        input,
+        Link {
+            path: path.into(),
+            desc: desc.map(Into::into),
+        },
+    ))
+}
+
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        Link::parse("[[#id]]"),
+        parse_link::<VerboseError<&str>>("[[#id]]"),
         Ok((
             "",
             Link {
@@ -62,7 +70,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Link::parse("[[#id][desc]]"),
+        parse_link::<VerboseError<&str>>("[[#id][desc]]"),
         Ok((
             "",
             Link {
@@ -71,5 +79,5 @@ fn parse() {
             }
         ))
     );
-    assert!(Link::parse("[[#id][desc]").is_err());
+    assert!(parse_link::<VerboseError<&str>>("[[#id][desc]").is_err());
 }
diff --git a/orgize/src/elements/macros.rs b/orgize/src/elements/macros.rs
index 77b304e..a5985e7 100644
--- a/orgize/src/elements/macros.rs
+++ b/orgize/src/elements/macros.rs
@@ -3,6 +3,7 @@ use std::borrow::Cow;
 use nom::{
     bytes::complete::{tag, take, take_until, take_while1},
     combinator::{opt, verify},
+    error::ParseError,
     sequence::delimited,
     IResult,
 };
@@ -20,23 +21,8 @@ pub struct Macros<'a> {
 }
 
 impl Macros<'_> {
-    #[inline]
-    pub(crate) fn parse(input: &str) -> IResult<&str, Macros<'_>> {
-        let (input, _) = tag("{{{")(input)?;
-        let (input, name) = verify(
-            take_while1(|c: char| c.is_ascii_alphanumeric() || c == '-' || c == '_'),
-            |s: &str| s.starts_with(|c: char| c.is_ascii_alphabetic()),
-        )(input)?;
-        let (input, arguments) = opt(delimited(tag("("), take_until(")}}}"), take(1usize)))(input)?;
-        let (input, _) = tag("}}}")(input)?;
-
-        Ok((
-            input,
-            Macros {
-                name: name.into(),
-                arguments: arguments.map(Into::into),
-            },
-        ))
+    pub(crate) fn parse(input: &str) -> Option<(&str, Macros<'_>)> {
+        parse_macros::<()>(input).ok()
     }
 
     pub fn into_owned(self) -> Macros<'static> {
@@ -47,10 +33,31 @@ impl Macros<'_> {
     }
 }
 
+#[inline]
+fn parse_macros<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, Macros<'a>, E> {
+    let (input, _) = tag("{{{")(input)?;
+    let (input, name) = verify(
+        take_while1(|c: char| c.is_ascii_alphanumeric() || c == '-' || c == '_'),
+        |s: &str| s.starts_with(|c: char| c.is_ascii_alphabetic()),
+    )(input)?;
+    let (input, arguments) = opt(delimited(tag("("), take_until(")}}}"), take(1usize)))(input)?;
+    let (input, _) = tag("}}}")(input)?;
+
+    Ok((
+        input,
+        Macros {
+            name: name.into(),
+            arguments: arguments.map(Into::into),
+        },
+    ))
+}
+
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        Macros::parse("{{{poem(red,blue)}}}"),
+        parse_macros::<VerboseError<&str>>("{{{poem(red,blue)}}}"),
         Ok((
             "",
             Macros {
@@ -60,7 +67,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Macros::parse("{{{poem())}}}"),
+        parse_macros::<VerboseError<&str>>("{{{poem())}}}"),
         Ok((
             "",
             Macros {
@@ -70,7 +77,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Macros::parse("{{{author}}}"),
+        parse_macros::<VerboseError<&str>>("{{{author}}}"),
         Ok((
             "",
             Macros {
@@ -79,8 +86,8 @@ fn parse() {
             }
         ))
     );
-    assert!(Macros::parse("{{{0uthor}}}").is_err());
-    assert!(Macros::parse("{{{author}}").is_err());
-    assert!(Macros::parse("{{{poem(}}}").is_err());
-    assert!(Macros::parse("{{{poem)}}}").is_err());
+    assert!(parse_macros::<VerboseError<&str>>("{{{0uthor}}}").is_err());
+    assert!(parse_macros::<VerboseError<&str>>("{{{author}}").is_err());
+    assert!(parse_macros::<VerboseError<&str>>("{{{poem(}}}").is_err());
+    assert!(parse_macros::<VerboseError<&str>>("{{{poem)}}}").is_err());
 }
diff --git a/orgize/src/elements/mod.rs b/orgize/src/elements/mod.rs
index 8a48a31..56e1510 100644
--- a/orgize/src/elements/mod.rs
+++ b/orgize/src/elements/mod.rs
@@ -1,32 +1,27 @@
 //! Org-mode elements
 
-mod block;
-mod clock;
-mod cookie;
-mod drawer;
-mod dyn_block;
-mod emphasis;
-mod fn_def;
-mod fn_ref;
-mod inline_call;
-mod inline_src;
-mod keyword;
-mod link;
-mod list;
-mod macros;
-mod planning;
-mod radio_target;
-mod rule;
-mod snippet;
-mod table;
-mod target;
-mod timestamp;
-mod title;
-
-pub(crate) use self::{
-    block::parse_block_element, emphasis::parse_emphasis, keyword::parse_keyword,
-    radio_target::parse_radio_target, rule::parse_rule, table::parse_table_el,
-};
+pub(crate) mod block;
+pub(crate) mod clock;
+pub(crate) mod cookie;
+pub(crate) mod drawer;
+pub(crate) mod dyn_block;
+pub(crate) mod emphasis;
+pub(crate) mod fn_def;
+pub(crate) mod fn_ref;
+pub(crate) mod inline_call;
+pub(crate) mod inline_src;
+pub(crate) mod keyword;
+pub(crate) mod link;
+pub(crate) mod list;
+pub(crate) mod macros;
+pub(crate) mod planning;
+pub(crate) mod radio_target;
+pub(crate) mod rule;
+pub(crate) mod snippet;
+pub(crate) mod table;
+pub(crate) mod target;
+pub(crate) mod timestamp;
+pub(crate) mod title;
 
 pub use self::{
     block::{
diff --git a/orgize/src/elements/planning.rs b/orgize/src/elements/planning.rs
index c37e988..ddfc61c 100644
--- a/orgize/src/elements/planning.rs
+++ b/orgize/src/elements/planning.rs
@@ -30,23 +30,18 @@ impl Planning<'_> {
             let next = &tail[i + 1..].trim_start();
 
             macro_rules! set_timestamp {
-                ($timestamp:expr) => {
-                    if $timestamp.is_none() {
-                        let (new_tail, timestamp) = Timestamp::parse_active(next)
-                            .or_else(|_| Timestamp::parse_inactive(next))
-                            .ok()?;
-                        $timestamp = Some(timestamp);
-                        tail = new_tail.trim_start();
-                    } else {
-                        return None;
-                    }
-                };
+                ($timestamp:expr) => {{
+                    let (new_tail, timestamp) =
+                        Timestamp::parse_active(next).or(Timestamp::parse_inactive(next))?;
+                    $timestamp = Some(timestamp);
+                    tail = new_tail.trim_start();
+                }};
             }
 
             match &tail[..i] {
-                "DEADLINE:" => set_timestamp!(deadline),
-                "SCHEDULED:" => set_timestamp!(scheduled),
-                "CLOSED:" => set_timestamp!(closed),
+                "DEADLINE:" if deadline.is_none() => set_timestamp!(deadline),
+                "SCHEDULED:" if scheduled.is_none() => set_timestamp!(scheduled),
+                "CLOSED:" if closed.is_none() => set_timestamp!(closed),
                 _ => return None,
             }
         }
diff --git a/orgize/src/elements/radio_target.rs b/orgize/src/elements/radio_target.rs
index 84c14c5..c5da94c 100644
--- a/orgize/src/elements/radio_target.rs
+++ b/orgize/src/elements/radio_target.rs
@@ -1,6 +1,7 @@
 use nom::{
     bytes::complete::{tag, take_while},
     combinator::verify,
+    error::ParseError,
     sequence::delimited,
     IResult,
 };
@@ -8,7 +9,14 @@ use nom::{
 // TODO: text-markup, entities, latex-fragments, subscript and superscript
 
 #[inline]
-pub(crate) fn parse_radio_target(input: &str) -> IResult<&str, &str> {
+pub fn parse_radio_target(input: &str) -> Option<(&str, &str)> {
+    parse_radio_target_internal::<()>(input).ok()
+}
+
+#[inline]
+fn parse_radio_target_internal<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, &'a str, E> {
     let (input, contents) = delimited(
         tag("<<<"),
         verify(
@@ -23,12 +31,20 @@ pub(crate) fn parse_radio_target(input: &str) -> IResult<&str, &str> {
 
 #[test]
 fn parse() {
-    assert_eq!(parse_radio_target("<<<target>>>"), Ok(("", "target")));
-    assert_eq!(parse_radio_target("<<<tar get>>>"), Ok(("", "tar get")));
-    assert!(parse_radio_target("<<<target >>>").is_err());
-    assert!(parse_radio_target("<<< target>>>").is_err());
-    assert!(parse_radio_target("<<<ta<get>>>").is_err());
-    assert!(parse_radio_target("<<<ta>get>>>").is_err());
-    assert!(parse_radio_target("<<<ta\nget>>>").is_err());
-    assert!(parse_radio_target("<<<target>>").is_err());
+    use nom::error::VerboseError;
+
+    assert_eq!(
+        parse_radio_target_internal::<VerboseError<&str>>("<<<target>>>"),
+        Ok(("", "target"))
+    );
+    assert_eq!(
+        parse_radio_target_internal::<VerboseError<&str>>("<<<tar get>>>"),
+        Ok(("", "tar get"))
+    );
+    assert!(parse_radio_target_internal::<VerboseError<&str>>("<<<target >>>").is_err());
+    assert!(parse_radio_target_internal::<VerboseError<&str>>("<<< target>>>").is_err());
+    assert!(parse_radio_target_internal::<VerboseError<&str>>("<<<ta<get>>>").is_err());
+    assert!(parse_radio_target_internal::<VerboseError<&str>>("<<<ta>get>>>").is_err());
+    assert!(parse_radio_target_internal::<VerboseError<&str>>("<<<ta\nget>>>").is_err());
+    assert!(parse_radio_target_internal::<VerboseError<&str>>("<<<target>>").is_err());
 }
diff --git a/orgize/src/elements/rule.rs b/orgize/src/elements/rule.rs
index c0b5e13..26692f2 100644
--- a/orgize/src/elements/rule.rs
+++ b/orgize/src/elements/rule.rs
@@ -1,10 +1,16 @@
 use std::usize;
 
-use nom::{bytes::complete::take_while_m_n, IResult};
+use nom::{bytes::complete::take_while_m_n, error::ParseError, IResult};
 
 use crate::parsers::eol;
 
-pub(crate) fn parse_rule(input: &str) -> IResult<&str, ()> {
+pub fn parse_rule(input: &str) -> Option<&str> {
+    parse_rule_internal::<()>(input)
+        .ok()
+        .map(|(input, _)| input)
+}
+
+fn parse_rule_internal<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, (), E> {
     let (input, _) = take_while_m_n(5, usize::MAX, |c| c == '-')(input)?;
     let (input, _) = eol(input)?;
     Ok((input, ()))
@@ -12,18 +18,32 @@ pub(crate) fn parse_rule(input: &str) -> IResult<&str, ()> {
 
 #[test]
 fn parse() {
-    assert_eq!(parse_rule("-----"), Ok(("", ())));
-    assert_eq!(parse_rule("--------"), Ok(("", ())));
-    assert_eq!(parse_rule("-----\n"), Ok(("", ())));
-    assert_eq!(parse_rule("-----  \n"), Ok(("", ())));
-    assert!(parse_rule("").is_err());
-    assert!(parse_rule("----").is_err());
-    assert!(parse_rule("----").is_err());
-    assert!(parse_rule("None----").is_err());
-    assert!(parse_rule("None  ----").is_err());
-    assert!(parse_rule("None------").is_err());
-    assert!(parse_rule("----None----").is_err());
-    assert!(parse_rule("\t\t----").is_err());
-    assert!(parse_rule("------None").is_err());
-    assert!(parse_rule("----- None").is_err());
+    use nom::error::VerboseError;
+
+    assert_eq!(
+        parse_rule_internal::<VerboseError<&str>>("-----"),
+        Ok(("", ()))
+    );
+    assert_eq!(
+        parse_rule_internal::<VerboseError<&str>>("--------"),
+        Ok(("", ()))
+    );
+    assert_eq!(
+        parse_rule_internal::<VerboseError<&str>>("-----\n"),
+        Ok(("", ()))
+    );
+    assert_eq!(
+        parse_rule_internal::<VerboseError<&str>>("-----  \n"),
+        Ok(("", ()))
+    );
+    assert!(parse_rule_internal::<VerboseError<&str>>("").is_err());
+    assert!(parse_rule_internal::<VerboseError<&str>>("----").is_err());
+    assert!(parse_rule_internal::<VerboseError<&str>>("----").is_err());
+    assert!(parse_rule_internal::<VerboseError<&str>>("None----").is_err());
+    assert!(parse_rule_internal::<VerboseError<&str>>("None  ----").is_err());
+    assert!(parse_rule_internal::<VerboseError<&str>>("None------").is_err());
+    assert!(parse_rule_internal::<VerboseError<&str>>("----None----").is_err());
+    assert!(parse_rule_internal::<VerboseError<&str>>("\t\t----").is_err());
+    assert!(parse_rule_internal::<VerboseError<&str>>("------None").is_err());
+    assert!(parse_rule_internal::<VerboseError<&str>>("----- None").is_err());
 }
diff --git a/orgize/src/elements/snippet.rs b/orgize/src/elements/snippet.rs
index 865f6f0..8280c04 100644
--- a/orgize/src/elements/snippet.rs
+++ b/orgize/src/elements/snippet.rs
@@ -2,6 +2,7 @@ use std::borrow::Cow;
 
 use nom::{
     bytes::complete::{tag, take, take_until, take_while1},
+    error::ParseError,
     sequence::{delimited, separated_pair},
     IResult,
 };
@@ -18,25 +19,8 @@ pub struct Snippet<'a> {
 }
 
 impl Snippet<'_> {
-    #[inline]
-    pub(crate) fn parse(input: &str) -> IResult<&str, Snippet<'_>> {
-        let (input, (name, value)) = delimited(
-            tag("@@"),
-            separated_pair(
-                take_while1(|c: char| c.is_ascii_alphanumeric() || c == '-'),
-                tag(":"),
-                take_until("@@"),
-            ),
-            take(2usize),
-        )(input)?;
-
-        Ok((
-            input,
-            Snippet {
-                name: name.into(),
-                value: value.into(),
-            },
-        ))
+    pub(crate) fn parse(input: &str) -> Option<(&str, Snippet<'_>)> {
+        parse_snippet::<()>(input).ok()
     }
 
     pub fn into_owned(self) -> Snippet<'static> {
@@ -47,10 +31,33 @@ impl Snippet<'_> {
     }
 }
 
+#[inline]
+fn parse_snippet<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, Snippet<'a>, E> {
+    let (input, (name, value)) = delimited(
+        tag("@@"),
+        separated_pair(
+            take_while1(|c: char| c.is_ascii_alphanumeric() || c == '-'),
+            tag(":"),
+            take_until("@@"),
+        ),
+        take(2usize),
+    )(input)?;
+
+    Ok((
+        input,
+        Snippet {
+            name: name.into(),
+            value: value.into(),
+        },
+    ))
+}
+
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        Snippet::parse("@@html:<b>@@"),
+        parse_snippet::<VerboseError<&str>>("@@html:<b>@@"),
         Ok((
             "",
             Snippet {
@@ -60,7 +67,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Snippet::parse("@@latex:any arbitrary LaTeX code@@"),
+        parse_snippet::<VerboseError<&str>>("@@latex:any arbitrary LaTeX code@@"),
         Ok((
             "",
             Snippet {
@@ -70,7 +77,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Snippet::parse("@@html:@@"),
+        parse_snippet::<VerboseError<&str>>("@@html:@@"),
         Ok((
             "",
             Snippet {
@@ -80,7 +87,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Snippet::parse("@@html:<p>@</p>@@"),
+        parse_snippet::<VerboseError<&str>>("@@html:<p>@</p>@@"),
         Ok((
             "",
             Snippet {
@@ -89,7 +96,7 @@ fn parse() {
             }
         ))
     );
-    assert!(Snippet::parse("@@html:<b>@").is_err());
-    assert!(Snippet::parse("@@html<b>@@").is_err());
-    assert!(Snippet::parse("@@:<b>@@").is_err());
+    assert!(parse_snippet::<VerboseError<&str>>("@@html:<b>@").is_err());
+    assert!(parse_snippet::<VerboseError<&str>>("@@html<b>@@").is_err());
+    assert!(parse_snippet::<VerboseError<&str>>("@@:<b>@@").is_err());
 }
diff --git a/orgize/src/elements/table.rs b/orgize/src/elements/table.rs
index 41407e8..522050d 100644
--- a/orgize/src/elements/table.rs
+++ b/orgize/src/elements/table.rs
@@ -2,6 +2,7 @@ use std::borrow::Cow;
 
 use nom::{
     combinator::{peek, verify},
+    error::ParseError,
     IResult,
 };
 
@@ -57,19 +58,30 @@ impl TableRow {
     }
 }
 
-pub(crate) fn parse_table_el(input: &str) -> IResult<&str, &str> {
+pub(crate) fn parse_table_el(input: &str) -> Option<(&str, &str)> {
+    parse_table_el_internal::<()>(input).ok()
+}
+
+fn parse_table_el_internal<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, &'a str, E> {
     let (input, _) = peek(verify(line, |s: &str| {
         let s = s.trim();
         s.starts_with("+-") && s.as_bytes().iter().all(|&c| c == b'+' || c == b'-')
     }))(input)?;
 
-    take_lines_while(|line| line.starts_with('|') || line.starts_with('+'))(input)
+    let (input, content) =
+        take_lines_while(|line| line.starts_with('|') || line.starts_with('+'))(input);
+
+    Ok((input, content))
 }
 
 #[test]
 fn parse_table_el_() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        parse_table_el(
+        parse_table_el_internal::<VerboseError<&str>>(
             r#"+---+
 |   |
 +---+
@@ -85,6 +97,6 @@ fn parse_table_el_() {
 "#
         ))
     );
-    assert!(parse_table_el("").is_err());
-    assert!(parse_table_el("+----|---").is_err());
+    assert!(parse_table_el_internal::<VerboseError<&str>>("").is_err());
+    assert!(parse_table_el_internal::<VerboseError<&str>>("+----|---").is_err());
 }
diff --git a/orgize/src/elements/target.rs b/orgize/src/elements/target.rs
index 44a1c2d..ccf235f 100644
--- a/orgize/src/elements/target.rs
+++ b/orgize/src/elements/target.rs
@@ -3,6 +3,7 @@ use std::borrow::Cow;
 use nom::{
     bytes::complete::{tag, take_while},
     combinator::verify,
+    error::ParseError,
     sequence::delimited,
     IResult,
 };
@@ -18,22 +19,8 @@ pub struct Target<'a> {
 
 impl Target<'_> {
     #[inline]
-    pub(crate) fn parse(input: &str) -> IResult<&str, Target<'_>> {
-        let (input, target) = delimited(
-            tag("<<"),
-            verify(
-                take_while(|c: char| c != '<' && c != '\n' && c != '>'),
-                |s: &str| s.starts_with(|c| c != ' ') && s.ends_with(|c| c != ' '),
-            ),
-            tag(">>"),
-        )(input)?;
-
-        Ok((
-            input,
-            Target {
-                target: target.into(),
-            },
-        ))
+    pub(crate) fn parse(input: &str) -> Option<(&str, Target<'_>)> {
+        parse_target::<()>(input).ok()
     }
 
     pub fn into_owned(self) -> Target<'static> {
@@ -43,10 +30,31 @@ impl Target<'_> {
     }
 }
 
+#[inline]
+fn parse_target<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, Target<'a>, E> {
+    let (input, target) = delimited(
+        tag("<<"),
+        verify(
+            take_while(|c: char| c != '<' && c != '\n' && c != '>'),
+            |s: &str| s.starts_with(|c| c != ' ') && s.ends_with(|c| c != ' '),
+        ),
+        tag(">>"),
+    )(input)?;
+
+    Ok((
+        input,
+        Target {
+            target: target.into(),
+        },
+    ))
+}
+
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        Target::parse("<<target>>"),
+        parse_target::<VerboseError<&str>>("<<target>>"),
         Ok((
             "",
             Target {
@@ -55,7 +63,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Target::parse("<<tar get>>"),
+        parse_target::<VerboseError<&str>>("<<tar get>>"),
         Ok((
             "",
             Target {
@@ -63,10 +71,10 @@ fn parse() {
             }
         ))
     );
-    assert!(Target::parse("<<target >>").is_err());
-    assert!(Target::parse("<< target>>").is_err());
-    assert!(Target::parse("<<ta<get>>").is_err());
-    assert!(Target::parse("<<ta>get>>").is_err());
-    assert!(Target::parse("<<ta\nget>>").is_err());
-    assert!(Target::parse("<<target>").is_err());
+    assert!(parse_target::<VerboseError<&str>>("<<target >>").is_err());
+    assert!(parse_target::<VerboseError<&str>>("<< target>>").is_err());
+    assert!(parse_target::<VerboseError<&str>>("<<ta<get>>").is_err());
+    assert!(parse_target::<VerboseError<&str>>("<<ta>get>>").is_err());
+    assert!(parse_target::<VerboseError<&str>>("<<ta\nget>>").is_err());
+    assert!(parse_target::<VerboseError<&str>>("<<target>").is_err());
 }
diff --git a/orgize/src/elements/timestamp.rs b/orgize/src/elements/timestamp.rs
index 3d5afbc..a5527dc 100644
--- a/orgize/src/elements/timestamp.rs
+++ b/orgize/src/elements/timestamp.rs
@@ -4,6 +4,7 @@ use nom::{
     bytes::complete::{tag, take, take_till, take_while, take_while_m_n},
     character::complete::{space0, space1},
     combinator::{map, map_res, opt},
+    error::ParseError,
     sequence::preceded,
     IResult,
 };
@@ -137,123 +138,16 @@ pub enum Timestamp<'a> {
 }
 
 impl Timestamp<'_> {
-    pub(crate) fn parse_active(input: &str) -> IResult<&str, Timestamp<'_>> {
-        let (input, _) = tag("<")(input)?;
-        let (input, start) = parse_datetime(input)?;
-
-        if input.starts_with('-') {
-            let (input, (hour, minute)) = parse_time(&input[1..])?;
-            let (input, _) = space0(input)?;
-            // TODO: delay-or-repeater
-            let (input, _) = tag(">")(input)?;
-            let mut end = start.clone();
-            end.hour = Some(hour);
-            end.minute = Some(minute);
-            return Ok((
-                input,
-                Timestamp::ActiveRange {
-                    start,
-                    end,
-                    repeater: None,
-                    delay: None,
-                },
-            ));
-        }
-
-        let (input, _) = space0(input)?;
-        // TODO: delay-or-repeater
-        let (input, _) = tag(">")(input)?;
-
-        if input.starts_with("--<") {
-            let (input, end) = parse_datetime(&input["--<".len()..])?;
-            let (input, _) = space0(input)?;
-            // TODO: delay-or-repeater
-            let (input, _) = tag(">")(input)?;
-            Ok((
-                input,
-                Timestamp::ActiveRange {
-                    start,
-                    end,
-                    repeater: None,
-                    delay: None,
-                },
-            ))
-        } else {
-            Ok((
-                input,
-                Timestamp::Active {
-                    start,
-                    repeater: None,
-                    delay: None,
-                },
-            ))
-        }
+    pub(crate) fn parse_active(input: &str) -> Option<(&str, Timestamp<'_>)> {
+        parse_active::<()>(input).ok()
     }
 
-    pub(crate) fn parse_inactive(input: &str) -> IResult<&str, Timestamp<'_>> {
-        let (input, _) = tag("[")(input)?;
-        let (input, start) = parse_datetime(input)?;
-
-        if input.starts_with('-') {
-            let (input, (hour, minute)) = parse_time(&input[1..])?;
-            let (input, _) = space0(input)?;
-            // TODO: delay-or-repeater
-            let (input, _) = tag("]")(input)?;
-            let mut end = start.clone();
-            end.hour = Some(hour);
-            end.minute = Some(minute);
-            return Ok((
-                input,
-                Timestamp::InactiveRange {
-                    start,
-                    end,
-                    repeater: None,
-                    delay: None,
-                },
-            ));
-        }
-
-        let (input, _) = space0(input)?;
-        // TODO: delay-or-repeater
-        let (input, _) = tag("]")(input)?;
-
-        if input.starts_with("--[") {
-            let (input, end) = parse_datetime(&input["--[".len()..])?;
-            let (input, _) = space0(input)?;
-            // TODO: delay-or-repeater
-            let (input, _) = tag("]")(input)?;
-            Ok((
-                input,
-                Timestamp::InactiveRange {
-                    start,
-                    end,
-                    repeater: None,
-                    delay: None,
-                },
-            ))
-        } else {
-            Ok((
-                input,
-                Timestamp::Inactive {
-                    start,
-                    repeater: None,
-                    delay: None,
-                },
-            ))
-        }
+    pub(crate) fn parse_inactive(input: &str) -> Option<(&str, Timestamp<'_>)> {
+        parse_inactive::<()>(input).ok()
     }
 
-    pub(crate) fn parse_diary(input: &str) -> IResult<&str, Timestamp<'_>> {
-        let (input, _) = tag("<%%(")(input)?;
-        let (input, value) = take_till(|c| c == ')' || c == '>' || c == '\n')(input)?;
-        let (input, _) = tag(")>")(input)?;
-
-        Ok((
-            input,
-            Timestamp::Diary {
-                value: value.into(),
-            },
-        ))
+    pub(crate) fn parse_diary(input: &str) -> Option<(&str, Timestamp<'_>)> {
+        parse_diary::<()>(input).ok()
     }
 
     pub fn into_owned(self) -> Timestamp<'static> {
@@ -305,7 +199,132 @@ impl Timestamp<'_> {
     }
 }
 
-fn parse_time(input: &str) -> IResult<&str, (u8, u8)> {
+pub fn parse_active<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, Timestamp<'a>, E> {
+    let (input, _) = tag("<")(input)?;
+    let (input, start) = parse_datetime(input)?;
+
+    if input.starts_with('-') {
+        let (input, (hour, minute)) = parse_time(&input[1..])?;
+        let (input, _) = space0(input)?;
+        // TODO: delay-or-repeater
+        let (input, _) = tag(">")(input)?;
+        let mut end = start.clone();
+        end.hour = Some(hour);
+        end.minute = Some(minute);
+        return Ok((
+            input,
+            Timestamp::ActiveRange {
+                start,
+                end,
+                repeater: None,
+                delay: None,
+            },
+        ));
+    }
+
+    let (input, _) = space0(input)?;
+    // TODO: delay-or-repeater
+    let (input, _) = tag(">")(input)?;
+
+    if input.starts_with("--<") {
+        let (input, end) = parse_datetime(&input["--<".len()..])?;
+        let (input, _) = space0(input)?;
+        // TODO: delay-or-repeater
+        let (input, _) = tag(">")(input)?;
+        Ok((
+            input,
+            Timestamp::ActiveRange {
+                start,
+                end,
+                repeater: None,
+                delay: None,
+            },
+        ))
+    } else {
+        Ok((
+            input,
+            Timestamp::Active {
+                start,
+                repeater: None,
+                delay: None,
+            },
+        ))
+    }
+}
+
+pub fn parse_inactive<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, Timestamp<'a>, E> {
+    let (input, _) = tag("[")(input)?;
+    let (input, start) = parse_datetime(input)?;
+
+    if input.starts_with('-') {
+        let (input, (hour, minute)) = parse_time(&input[1..])?;
+        let (input, _) = space0(input)?;
+        // TODO: delay-or-repeater
+        let (input, _) = tag("]")(input)?;
+        let mut end = start.clone();
+        end.hour = Some(hour);
+        end.minute = Some(minute);
+        return Ok((
+            input,
+            Timestamp::InactiveRange {
+                start,
+                end,
+                repeater: None,
+                delay: None,
+            },
+        ));
+    }
+
+    let (input, _) = space0(input)?;
+    // TODO: delay-or-repeater
+    let (input, _) = tag("]")(input)?;
+
+    if input.starts_with("--[") {
+        let (input, end) = parse_datetime(&input["--[".len()..])?;
+        let (input, _) = space0(input)?;
+        // TODO: delay-or-repeater
+        let (input, _) = tag("]")(input)?;
+        Ok((
+            input,
+            Timestamp::InactiveRange {
+                start,
+                end,
+                repeater: None,
+                delay: None,
+            },
+        ))
+    } else {
+        Ok((
+            input,
+            Timestamp::Inactive {
+                start,
+                repeater: None,
+                delay: None,
+            },
+        ))
+    }
+}
+
+pub fn parse_diary<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, Timestamp<'a>, E> {
+    let (input, _) = tag("<%%(")(input)?;
+    let (input, value) = take_till(|c| c == ')' || c == '>' || c == '\n')(input)?;
+    let (input, _) = tag(")>")(input)?;
+
+    Ok((
+        input,
+        Timestamp::Diary {
+            value: value.into(),
+        },
+    ))
+}
+
+fn parse_time<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, (u8, u8), E> {
     let (input, hour) = map_res(take_while_m_n(1, 2, |c: char| c.is_ascii_digit()), |num| {
         u8::from_str_radix(num, 10)
     })(input)?;
@@ -314,7 +333,7 @@ fn parse_time(input: &str) -> IResult<&str, (u8, u8)> {
     Ok((input, (hour, minute)))
 }
 
-fn parse_datetime(input: &str) -> IResult<&str, Datetime<'_>> {
+fn parse_datetime<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, Datetime<'a>, E> {
     let parse_u8 = |num| u8::from_str_radix(num, 10);
 
     let (input, year) = map_res(take(4usize), |num| u16::from_str_radix(num, 10))(input)?;
@@ -397,8 +416,10 @@ fn parse_datetime(input: &str) -> IResult<&str, Datetime<'_>> {
 
 #[test]
 fn parse() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        Timestamp::parse_inactive("[2003-09-16 Tue]"),
+        parse_inactive::<VerboseError<&str>>("[2003-09-16 Tue]"),
         Ok((
             "",
             Timestamp::Inactive {
@@ -416,7 +437,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Timestamp::parse_inactive("[2003-09-16 Tue 09:39]--[2003-09-16 Tue 10:39]"),
+        parse_inactive::<VerboseError<&str>>("[2003-09-16 Tue 09:39]--[2003-09-16 Tue 10:39]"),
         Ok((
             "",
             Timestamp::InactiveRange {
@@ -442,7 +463,7 @@ fn parse() {
         ))
     );
     assert_eq!(
-        Timestamp::parse_active("<2003-09-16 Tue 09:39-10:39>"),
+        parse_active::<VerboseError<&str>>("<2003-09-16 Tue 09:39-10:39>"),
         Ok((
             "",
             Timestamp::ActiveRange {
diff --git a/orgize/src/elements/title.rs b/orgize/src/elements/title.rs
index f231f23..405199e 100644
--- a/orgize/src/elements/title.rs
+++ b/orgize/src/elements/title.rs
@@ -8,15 +8,14 @@ use nom::{
     bytes::complete::{tag, take_until, take_while},
     character::complete::{anychar, space1},
     combinator::{map, map_parser, opt, verify},
-    error::ErrorKind,
-    error_position,
+    error::{ErrorKind, ParseError},
     multi::fold_many0,
     sequence::{delimited, preceded},
     Err, IResult,
 };
 
 use crate::config::ParseConfig;
-use crate::elements::{Drawer, Planning, Timestamp};
+use crate::elements::{drawer::parse_drawer, Planning, Timestamp};
 use crate::parsers::{line, skip_empty_lines, take_one_word};
 
 /// Title Elemenet
@@ -46,68 +45,11 @@ pub struct Title<'a> {
 }
 
 impl Title<'_> {
-    #[inline]
     pub(crate) fn parse<'a>(
         input: &'a str,
         config: &ParseConfig,
-    ) -> IResult<&'a str, (Title<'a>, &'a str)> {
-        let (input, level) = map(take_while(|c: char| c == '*'), |s: &str| s.len())(input)?;
-
-        debug_assert!(level > 0);
-
-        let (input, keyword) = opt(preceded(
-            space1,
-            verify(take_one_word, |s: &str| {
-                config.todo_keywords.iter().any(|x| x == s)
-                    || config.done_keywords.iter().any(|x| x == s)
-            }),
-        ))(input)?;
-
-        let (input, priority) = opt(preceded(
-            space1,
-            map_parser(
-                take_one_word,
-                delimited(
-                    tag("[#"),
-                    verify(anychar, |c: &char| c.is_ascii_uppercase()),
-                    tag("]"),
-                ),
-            ),
-        ))(input)?;
-        let (input, tail) = line(input)?;
-        let tail = tail.trim();
-        let (raw, tags) = memrchr(b' ', tail.as_bytes())
-            .map(|i| (tail[0..i].trim(), &tail[i + 1..]))
-            .filter(|(_, x)| x.len() > 2 && x.starts_with(':') && x.ends_with(':'))
-            .unwrap_or((tail, ""));
-
-        let tags = tags
-            .split(':')
-            .filter(|s| !s.is_empty())
-            .map(Into::into)
-            .collect();
-
-        let (input, planning) = Planning::parse(input)
-            .map(|(input, planning)| (input, Some(Box::new(planning))))
-            .unwrap_or((input, None));
-
-        let (input, properties) = opt(parse_properties_drawer)(input)?;
-
-        Ok((
-            input,
-            (
-                Title {
-                    properties: properties.unwrap_or_default(),
-                    level,
-                    keyword: keyword.map(Into::into),
-                    priority,
-                    tags,
-                    raw: raw.into(),
-                    planning,
-                },
-                raw,
-            ),
-        ))
+    ) -> Option<(&'a str, (Title<'a>, &'a str))> {
+        parse_title::<()>(input, config).ok()
     }
 
     // TODO: fn is_archived(&self) -> bool { }
@@ -136,6 +78,11 @@ impl Title<'_> {
             .and_then(|planning| planning.deadline.as_ref())
     }
 
+    /// checks if this headline is "archived"
+    pub fn is_archived(&self) -> bool {
+        self.tags.iter().any(|tag| tag == "ARCHIVE")
+    }
+
     pub fn into_owned(self) -> Title<'static> {
         Title {
             level: self.level,
@@ -171,10 +118,77 @@ impl Default for Title<'_> {
     }
 }
 
-fn parse_properties_drawer(input: &str) -> IResult<&str, HashMap<Cow<'_, str>, Cow<'_, str>>> {
-    let (input, (drawer, content)) = Drawer::parse(input.trim_start())?;
+#[inline]
+fn parse_title<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+    config: &ParseConfig,
+) -> IResult<&'a str, (Title<'a>, &'a str), E> {
+    let (input, level) = map(take_while(|c: char| c == '*'), |s: &str| s.len())(input)?;
+
+    debug_assert!(level > 0);
+
+    let (input, keyword) = opt(preceded(
+        space1,
+        verify(take_one_word, |s: &str| {
+            config.todo_keywords.iter().any(|x| x == s)
+                || config.done_keywords.iter().any(|x| x == s)
+        }),
+    ))(input)?;
+
+    let (input, priority) = opt(preceded(
+        space1,
+        map_parser(
+            take_one_word,
+            delimited(
+                tag("[#"),
+                verify(anychar, |c: &char| c.is_ascii_uppercase()),
+                tag("]"),
+            ),
+        ),
+    ))(input)?;
+    let (input, tail) = line(input)?;
+    let tail = tail.trim();
+    let (raw, tags) = memrchr(b' ', tail.as_bytes())
+        .map(|i| (tail[0..i].trim(), &tail[i + 1..]))
+        .filter(|(_, x)| x.len() > 2 && x.starts_with(':') && x.ends_with(':'))
+        .unwrap_or((tail, ""));
+
+    let tags = tags
+        .split(':')
+        .filter(|s| !s.is_empty())
+        .map(Into::into)
+        .collect();
+
+    let (input, planning) = Planning::parse(input)
+        .map(|(input, planning)| (input, Some(Box::new(planning))))
+        .unwrap_or((input, None));
+
+    let (input, properties) = opt(parse_properties_drawer)(input)?;
+
+    Ok((
+        input,
+        (
+            Title {
+                properties: properties.unwrap_or_default(),
+                level,
+                keyword: keyword.map(Into::into),
+                priority,
+                tags,
+                raw: raw.into(),
+                planning,
+            },
+            raw,
+        ),
+    ))
+}
+
+#[inline]
+fn parse_properties_drawer<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, HashMap<Cow<'a, str>, Cow<'a, str>>, E> {
+    let (input, (drawer, content)) = parse_drawer(input.trim_start())?;
     if drawer.name != "PROPERTIES" {
-        return Err(Err::Error(error_position!(input, ErrorKind::Tag)));
+        return Err(Err::Error(E::from_error_kind(input, ErrorKind::Tag)));
     }
     let (_, map) = fold_many0(
         parse_node_property,
@@ -187,7 +201,10 @@ fn parse_properties_drawer(input: &str) -> IResult<&str, HashMap<Cow<'_, str>, C
     Ok((input, map))
 }
 
-fn parse_node_property(input: &str) -> IResult<&str, (&str, &str)> {
+#[inline]
+fn parse_node_property<'a, E: ParseError<&'a str>>(
+    input: &'a str,
+) -> IResult<&'a str, (&'a str, &'a str), E> {
     let input = skip_empty_lines(input).trim_start();
     let (input, name) = map(delimited(tag(":"), take_until(":"), tag(":")), |s: &str| {
         s.trim_end_matches('+')
@@ -196,19 +213,17 @@ fn parse_node_property(input: &str) -> IResult<&str, (&str, &str)> {
     Ok((input, (name, value.trim())))
 }
 
-impl Title<'_> {
-    /// checks if this headline is "archived"
-    pub fn is_archived(&self) -> bool {
-        self.tags.iter().any(|tag| tag == "ARCHIVE")
-    }
-}
-
 #[test]
-fn parse_title() {
+fn parse_title_() {
+    use nom::error::VerboseError;
+
     use crate::config::DEFAULT_CONFIG;
 
     assert_eq!(
-        Title::parse("**** DONE [#A] COMMENT Title :tag:a2%:", &DEFAULT_CONFIG),
+        parse_title::<VerboseError<&str>>(
+            "**** DONE [#A] COMMENT Title :tag:a2%:",
+            &DEFAULT_CONFIG
+        ),
         Ok((
             "",
             (
@@ -226,7 +241,7 @@ fn parse_title() {
         ))
     );
     assert_eq!(
-        Title::parse("**** ToDO [#A] COMMENT Title", &DEFAULT_CONFIG),
+        parse_title::<VerboseError<&str>>("**** ToDO [#A] COMMENT Title", &DEFAULT_CONFIG),
         Ok((
             "",
             (
@@ -244,7 +259,7 @@ fn parse_title() {
         ))
     );
     assert_eq!(
-        Title::parse("**** T0DO [#A] COMMENT Title", &DEFAULT_CONFIG),
+        parse_title::<VerboseError<&str>>("**** T0DO [#A] COMMENT Title", &DEFAULT_CONFIG),
         Ok((
             "",
             (
@@ -262,7 +277,7 @@ fn parse_title() {
         ))
     );
     assert_eq!(
-        Title::parse("**** DONE [#1] COMMENT Title", &DEFAULT_CONFIG),
+        parse_title::<VerboseError<&str>>("**** DONE [#1] COMMENT Title", &DEFAULT_CONFIG),
         Ok((
             "",
             (
@@ -280,7 +295,7 @@ fn parse_title() {
         ))
     );
     assert_eq!(
-        Title::parse("**** DONE [#a] COMMENT Title", &DEFAULT_CONFIG),
+        parse_title::<VerboseError<&str>>("**** DONE [#a] COMMENT Title", &DEFAULT_CONFIG),
         Ok((
             "",
             (
@@ -298,7 +313,7 @@ fn parse_title() {
         ))
     );
     assert_eq!(
-        Title::parse("**** Title :tag:a2%", &DEFAULT_CONFIG),
+        parse_title::<VerboseError<&str>>("**** Title :tag:a2%", &DEFAULT_CONFIG),
         Ok((
             "",
             (
@@ -316,7 +331,7 @@ fn parse_title() {
         ))
     );
     assert_eq!(
-        Title::parse("**** Title tag:a2%:", &DEFAULT_CONFIG),
+        parse_title::<VerboseError<&str>>("**** Title tag:a2%:", &DEFAULT_CONFIG),
         Ok((
             "",
             (
@@ -335,7 +350,7 @@ fn parse_title() {
     );
 
     assert_eq!(
-        Title::parse(
+        parse_title::<VerboseError<&str>>(
             "**** DONE Title",
             &ParseConfig {
                 done_keywords: vec![],
@@ -359,7 +374,7 @@ fn parse_title() {
         ))
     );
     assert_eq!(
-        Title::parse(
+        parse_title::<VerboseError<&str>>(
             "**** TASK [#A] Title",
             &ParseConfig {
                 todo_keywords: vec!["TASK".to_string()],
@@ -386,8 +401,12 @@ fn parse_title() {
 
 #[test]
 fn parse_properties_drawer_() {
+    use nom::error::VerboseError;
+
     assert_eq!(
-        parse_properties_drawer("   :PROPERTIES:\n   :CUSTOM_ID: id\n   :END:"),
+        parse_properties_drawer::<VerboseError<&str>>(
+            "   :PROPERTIES:\n   :CUSTOM_ID: id\n   :END:"
+        ),
         Ok((
             "",
             vec![("CUSTOM_ID".into(), "id".into())]
@@ -399,14 +418,14 @@ fn parse_properties_drawer_() {
 
 // #[test]
 // fn is_commented() {
-//     assert!(Title::parse("* COMMENT Title", &DEFAULT_CONFIG)
+//     assert!(parse_title::<VerboseError<&str>>("* COMMENT Title", &DEFAULT_CONFIG)
 //         .1
 //         .is_commented());
-//     assert!(!Title::parse("* Title", &DEFAULT_CONFIG).1.is_commented());
-//     assert!(!Title::parse("* C0MMENT Title", &DEFAULT_CONFIG)
+//     assert!(!parse_title::<VerboseError<&str>>("* Title", &DEFAULT_CONFIG).1.is_commented());
+//     assert!(!parse_title::<VerboseError<&str>>("* C0MMENT Title", &DEFAULT_CONFIG)
 //         .1
 //         .is_commented());
-//     assert!(!Title::parse("* comment Title", &DEFAULT_CONFIG)
+//     assert!(!parse_title::<VerboseError<&str>>("* comment Title", &DEFAULT_CONFIG)
 //         .1
 //         .is_commented());
 // }
diff --git a/orgize/src/parsers.rs b/orgize/src/parsers.rs
index 8297ce5..472b501 100644
--- a/orgize/src/parsers.rs
+++ b/orgize/src/parsers.rs
@@ -7,13 +7,16 @@ use std::marker::PhantomData;
 use indextree::{Arena, NodeId};
 use jetscii::{bytes, BytesConst};
 use memchr::{memchr, memchr_iter};
-use nom::{
-    bytes::complete::take_while1, combinator::verify, error::ErrorKind, error_position, Err,
-    IResult,
-};
+use nom::{bytes::complete::take_while1, combinator::verify, error::ParseError, IResult};
 
 use crate::config::ParseConfig;
-use crate::elements::*;
+use crate::elements::{
+    block::parse_block_element, emphasis::parse_emphasis, keyword::parse_keyword,
+    radio_target::parse_radio_target, rule::parse_rule, table::parse_table_el, BabelCall,
+    CenterBlock, Clock, CommentBlock, Cookie, Drawer, DynBlock, Element, ExampleBlock, ExportBlock,
+    FnDef, FnRef, InlineCall, InlineSrc, Keyword, Link, List, ListItem, Macros, QuoteBlock,
+    Snippet, SourceBlock, SpecialBlock, Table, TableRow, Target, Timestamp, Title, VerseBlock,
+};
 
 pub trait ElementArena<'a> {
     fn append_element<T: Into<Element<'a>>>(&mut self, element: T, parent: NodeId) -> NodeId;
@@ -72,13 +75,8 @@ impl<'a> ElementArena<'a> for OwnedArena<'a, '_, '_> {
         element: T,
         parent: NodeId,
     ) -> NodeId {
-        if let Some(child) = self.arena[parent].last_child() {
-            let node = self.arena.new_node(element.into().into_owned());
-            child.insert_before(node, self.arena);
-            node
-        } else {
-            self.append_element(element, parent)
-        }
+        self.arena
+            .insert_before_last_child(element.into().into_owned(), parent)
     }
 }
 
@@ -170,7 +168,7 @@ pub fn parse_section_and_headlines<'a, T: ElementArena<'a>>(
 
     let mut last_end = 0;
     for i in memchr_iter(b'\n', content.as_bytes()).chain(once(content.len())) {
-        if let Ok((mut tail, (headline_content, level))) = parse_headline(&content[last_end..]) {
+        if let Some((mut tail, (headline_content, level))) = parse_headline(&content[last_end..]) {
             if last_end != 0 {
                 let node = arena.append_element(Element::Section, parent);
                 let content = &content[0..last_end];
@@ -183,7 +181,7 @@ pub fn parse_section_and_headlines<'a, T: ElementArena<'a>>(
                 node,
             });
 
-            while let Ok((new_tail, (content, level))) = parse_headline(tail) {
+            while let Some((new_tail, (content, level))) = parse_headline(tail) {
                 debug_assert_ne!(tail, new_tail);
                 let node = arena.append_element(Element::Headline { level }, parent);
                 containers.push(Container::Headline { content, node });
@@ -266,7 +264,7 @@ pub fn parse_block<'a, T: ElementArena<'a>>(
     parent: NodeId,
     containers: &mut Vec<Container<'a>>,
 ) -> Option<&'a str> {
-    if let Ok((tail, (fn_def, content))) = FnDef::parse(contents) {
+    if let Some((tail, (fn_def, content))) = FnDef::parse(contents) {
         let node = arena.append_element(fn_def, parent);
         containers.push(Container::Block { content, node });
         return Some(tail);
@@ -285,42 +283,37 @@ pub fn parse_block<'a, T: ElementArena<'a>>(
 
     match contents.as_bytes().get(0)? {
         b'C' => {
-            if let Ok((tail, clock)) = Clock::parse(contents) {
-                arena.append_element(clock, parent);
-                return Some(tail);
-            }
+            let (tail, clock) = Clock::parse(contents)?;
+            arena.append_element(clock, parent);
+            Some(tail)
         }
         b'\'' => {
             // TODO: LaTeX environment
+            None
         }
         b'-' => {
-            if let Ok((tail, _)) = parse_rule(contents) {
-                arena.append_element(Element::Rule, parent);
-                return Some(tail);
-            }
+            let tail = parse_rule(contents)?;
+            arena.append_element(Element::Rule, parent);
+            Some(tail)
         }
         b':' => {
-            if let Ok((tail, (drawer, content))) = Drawer::parse(contents) {
+            if let Some((tail, (drawer, content))) = Drawer::parse(contents) {
                 let node = arena.append_element(drawer, parent);
                 containers.push(Container::Block { content, node });
-                return Some(tail);
-            } else if let Ok((tail, value)) = parse_fixed_width(contents) {
-                arena.append_element(
-                    Element::FixedWidth {
-                        value: value.into(),
-                    },
-                    parent,
-                );
-                return Some(tail);
+                Some(tail)
+            } else {
+                let (tail, value) = parse_fixed_width(contents)?;
+                let value = value.into();
+                arena.append_element(Element::FixedWidth { value }, parent);
+                Some(tail)
             }
         }
         b'|' => {
-            if let Some(tail) = parse_table(arena, contents, containers, parent) {
-                return Some(tail);
-            }
+            let tail = parse_table(arena, contents, containers, parent)?;
+            Some(tail)
         }
         b'#' => {
-            if let Ok((tail, (name, args, content))) = parse_block_element(contents) {
+            if let Some((tail, (name, args, content))) = parse_block_element(contents) {
                 match_block(
                     arena,
                     parent,
@@ -329,12 +322,12 @@ pub fn parse_block<'a, T: ElementArena<'a>>(
                     args.map(Into::into),
                     content,
                 );
-                return Some(tail);
-            } else if let Ok((tail, (dyn_block, content))) = DynBlock::parse(contents) {
+                Some(tail)
+            } else if let Some((tail, (dyn_block, content))) = DynBlock::parse(contents) {
                 let node = arena.append_element(dyn_block, parent);
                 containers.push(Container::Block { content, node });
-                return Some(tail);
-            } else if let Ok((tail, (key, optional, value))) = parse_keyword(contents) {
+                Some(tail)
+            } else if let Some((tail, (key, optional, value))) = parse_keyword(contents) {
                 if (&*key).eq_ignore_ascii_case("CALL") {
                     arena.append_element(
                         BabelCall {
@@ -352,21 +345,16 @@ pub fn parse_block<'a, T: ElementArena<'a>>(
                         parent,
                     );
                 }
-                return Some(tail);
-            } else if let Ok((tail, value)) = parse_comment(contents) {
-                arena.append_element(
-                    Element::Comment {
-                        value: value.into(),
-                    },
-                    parent,
-                );
-                return Some(tail);
+                Some(tail)
+            } else {
+                let (tail, value) = parse_comment(contents)?;
+                let value = value.into();
+                arena.append_element(Element::Comment { value }, parent);
+                Some(tail)
             }
         }
-        _ => (),
+        _ => None,
     }
-
-    None
 }
 
 pub fn match_block<'a, T: ElementArena<'a>>(
@@ -542,116 +530,97 @@ pub fn parse_inline<'a, T: ElementArena<'a>>(
         return None;
     }
 
-    let bytes = contents.as_bytes();
-    match bytes[0] {
+    match contents.as_bytes()[0] {
         b'@' => {
-            if let Ok((tail, snippet)) = Snippet::parse(contents) {
-                arena.append_element(snippet, parent);
-                return Some(tail);
-            }
+            let (tail, snippet) = Snippet::parse(contents)?;
+            arena.append_element(snippet, parent);
+            Some(tail)
         }
         b'{' => {
-            if let Ok((tail, macros)) = Macros::parse(contents) {
-                arena.append_element(macros, parent);
-                return Some(tail);
-            }
+            let (tail, macros) = Macros::parse(contents)?;
+            arena.append_element(macros, parent);
+            Some(tail)
         }
         b'<' => {
-            if let Ok((tail, _content)) = parse_radio_target(contents) {
+            if let Some((tail, _content)) = parse_radio_target(contents) {
                 arena.append_element(Element::RadioTarget, parent);
-                return Some(tail);
-            } else if let Ok((tail, target)) = Target::parse(contents) {
+                Some(tail)
+            } else if let Some((tail, target)) = Target::parse(contents) {
                 arena.append_element(target, parent);
-                return Some(tail);
-            } else if let Ok((tail, timestamp)) = Timestamp::parse_active(contents) {
+                Some(tail)
+            } else if let Some((tail, timestamp)) = Timestamp::parse_active(contents) {
                 arena.append_element(timestamp, parent);
-                return Some(tail);
-            } else if let Ok((tail, timestamp)) = Timestamp::parse_diary(contents) {
+                Some(tail)
+            } else {
+                let (tail, timestamp) = Timestamp::parse_diary(contents)?;
                 arena.append_element(timestamp, parent);
-                return Some(tail);
+                Some(tail)
             }
         }
         b'[' => {
-            if let Ok((tail, fn_ref)) = FnRef::parse(contents) {
+            if let Some((tail, fn_ref)) = FnRef::parse(contents) {
                 arena.append_element(fn_ref, parent);
-                return Some(tail);
-            } else if let Ok((tail, link)) = Link::parse(contents) {
+                Some(tail)
+            } else if let Some((tail, link)) = Link::parse(contents) {
                 arena.append_element(link, parent);
-                return Some(tail);
-            } else if let Ok((tail, cookie)) = Cookie::parse(contents) {
+                Some(tail)
+            } else if let Some((tail, cookie)) = Cookie::parse(contents) {
                 arena.append_element(cookie, parent);
-                return Some(tail);
-            } else if let Ok((tail, timestamp)) = Timestamp::parse_inactive(contents) {
+                Some(tail)
+            } else {
+                let (tail, timestamp) = Timestamp::parse_inactive(contents)?;
                 arena.append_element(timestamp, parent);
-                return Some(tail);
+                Some(tail)
             }
         }
         b'*' => {
-            if let Some((tail, content)) = parse_emphasis(contents, b'*') {
-                let node = arena.append_element(Element::Bold, parent);
-                containers.push(Container::Inline { content, node });
-                return Some(tail);
-            }
+            let (tail, content) = parse_emphasis(contents, b'*')?;
+            let node = arena.append_element(Element::Bold, parent);
+            containers.push(Container::Inline { content, node });
+            Some(tail)
         }
         b'+' => {
-            if let Some((tail, content)) = parse_emphasis(contents, b'+') {
-                let node = arena.append_element(Element::Strike, parent);
-                containers.push(Container::Inline { content, node });
-                return Some(tail);
-            }
+            let (tail, content) = parse_emphasis(contents, b'+')?;
+            let node = arena.append_element(Element::Strike, parent);
+            containers.push(Container::Inline { content, node });
+            Some(tail)
         }
         b'/' => {
-            if let Some((tail, content)) = parse_emphasis(contents, b'/') {
-                let node = arena.append_element(Element::Italic, parent);
-                containers.push(Container::Inline { content, node });
-                return Some(tail);
-            }
+            let (tail, content) = parse_emphasis(contents, b'/')?;
+            let node = arena.append_element(Element::Italic, parent);
+            containers.push(Container::Inline { content, node });
+            Some(tail)
         }
         b'_' => {
-            if let Some((tail, content)) = parse_emphasis(contents, b'_') {
-                let node = arena.append_element(Element::Underline, parent);
-                containers.push(Container::Inline { content, node });
-                return Some(tail);
-            }
+            let (tail, content) = parse_emphasis(contents, b'_')?;
+            let node = arena.append_element(Element::Underline, parent);
+            containers.push(Container::Inline { content, node });
+            Some(tail)
         }
         b'=' => {
-            if let Some((tail, value)) = parse_emphasis(contents, b'=') {
-                arena.append_element(
-                    Element::Verbatim {
-                        value: value.into(),
-                    },
-                    parent,
-                );
-                return Some(tail);
-            }
+            let (tail, value) = parse_emphasis(contents, b'=')?;
+            let value = value.into();
+            arena.append_element(Element::Verbatim { value }, parent);
+            Some(tail)
         }
         b'~' => {
-            if let Some((tail, value)) = parse_emphasis(contents, b'~') {
-                arena.append_element(
-                    Element::Code {
-                        value: value.into(),
-                    },
-                    parent,
-                );
-                return Some(tail);
-            }
+            let (tail, value) = parse_emphasis(contents, b'~')?;
+            let value = value.into();
+            arena.append_element(Element::Code { value }, parent);
+            Some(tail)
         }
         b's' => {
-            if let Ok((tail, inline_src)) = InlineSrc::parse(contents) {
-                arena.append_element(inline_src, parent);
-                return Some(tail);
-            }
+            let (tail, inline_src) = InlineSrc::parse(contents)?;
+            arena.append_element(inline_src, parent);
+            Some(tail)
         }
         b'c' => {
-            if let Ok((tail, inline_call)) = InlineCall::parse(contents) {
-                arena.append_element(inline_call, parent);
-                return Some(tail);
-            }
+            let (tail, inline_call) = InlineCall::parse(contents)?;
+            arena.append_element(inline_call, parent);
+            Some(tail)
         }
-        _ => (),
+        _ => None,
     }
-
-    None
 }
 
 pub fn parse_list_items<'a, T: ElementArena<'a>>(
@@ -701,20 +670,16 @@ pub fn parse_table<'a, T: ElementArena<'a>>(
         }
 
         Some("")
-    } else if let Ok((tail, value)) = parse_table_el(contents) {
-        arena.append_element(
-            Table::TableEl {
-                value: value.into(),
-            },
-            parent,
-        );
-        Some(tail)
     } else {
-        None
+        let (tail, value) = parse_table_el(contents)?;
+        let value = value.into();
+        arena.append_element(Table::TableEl { value }, parent);
+
+        Some(tail)
     }
 }
 
-pub fn line(input: &str) -> IResult<&str, &str> {
+pub fn line<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, &'a str, E> {
     if let Some(i) = memchr(b'\n', input.as_bytes()) {
         if i > 0 && input.as_bytes()[i - 1] == b'\r' {
             Ok((&input[i + 1..], &input[0..i - 1]))
@@ -726,73 +691,76 @@ pub fn line(input: &str) -> IResult<&str, &str> {
     }
 }
 
-pub fn eol(input: &str) -> IResult<&str, &str> {
+pub fn eol<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, &'a str, E> {
     verify(line, |s: &str| s.trim().is_empty())(input)
 }
 
-pub fn take_lines_while(predicate: impl Fn(&str) -> bool) -> impl Fn(&str) -> IResult<&str, &str> {
+pub fn take_lines_while(predicate: impl Fn(&str) -> bool) -> impl Fn(&str) -> (&str, &str) {
     move |input| {
         let mut last_end = 0;
         for i in memchr_iter(b'\n', input.as_bytes()) {
             if i > 0 && input.as_bytes()[i - 1] == b'\r' {
                 if !predicate(&input[last_end..i - 1]) {
-                    return Ok((&input[last_end..], &input[0..last_end]));
+                    return (&input[last_end..], &input[0..last_end]);
                 }
             } else if !predicate(&input[last_end..i]) {
-                return Ok((&input[last_end..], &input[0..last_end]));
+                return (&input[last_end..], &input[0..last_end]);
             }
             last_end = i + 1;
         }
         if !predicate(&input[last_end..]) {
-            Ok((&input[last_end..], &input[0..last_end]))
+            (&input[last_end..], &input[0..last_end])
         } else {
-            Ok(("", input))
+            ("", input)
         }
     }
 }
 
 pub fn skip_empty_lines(input: &str) -> &str {
-    take_lines_while(|line| line.trim().is_empty())(input)
-        .map(|(tail, _)| tail)
-        .unwrap_or(input)
+    take_lines_while(|line| line.trim().is_empty())(input).0
 }
 
-pub fn parse_headline(input: &str) -> IResult<&str, (&str, usize)> {
+pub fn parse_headline(input: &str) -> Option<(&str, (&str, usize))> {
     let (input_, level) = parse_headline_level(input)?;
     let (input_, content) = take_lines_while(move |line| {
-        if let Ok((_, l)) = parse_headline_level(line) {
-            l > level
-        } else {
-            true
-        }
-    })(input_)?;
-    Ok((input_, (&input[0..level + content.len()], level)))
+        parse_headline_level(line)
+            .map(|(_, l)| l > level)
+            .unwrap_or(true)
+    })(input_);
+    Some((input_, (&input[0..level + content.len()], level)))
 }
 
-pub fn parse_headline_level(input: &str) -> IResult<&str, usize> {
-    let (input, stars) = take_while1(|c: char| c == '*')(input)?;
+pub fn parse_headline_level(input: &str) -> Option<(&str, usize)> {
+    let (input, stars) = take_while1::<_, _, ()>(|c: char| c == '*')(input).ok()?;
+
     if input.starts_with(' ') || input.starts_with('\n') || input.is_empty() {
-        Ok((input, stars.len()))
+        Some((input, stars.len()))
     } else {
-        Err(Err::Error(error_position!(input, ErrorKind::Tag)))
+        None
     }
 }
 
-pub fn parse_fixed_width(input: &str) -> IResult<&str, &str> {
-    verify(
-        take_lines_while(|line| line == ":" || line.starts_with(": ")),
-        |s: &str| !s.is_empty(),
-    )(input)
+pub fn parse_fixed_width(input: &str) -> Option<(&str, &str)> {
+    let (input, content) = take_lines_while(|line| line == ":" || line.starts_with(": "))(input);
+
+    if !content.is_empty() {
+        Some((input, content))
+    } else {
+        None
+    }
 }
 
-pub fn parse_comment(input: &str) -> IResult<&str, &str> {
-    verify(
-        take_lines_while(|line| line == "#" || line.starts_with("# ")),
-        |s: &str| !s.is_empty(),
-    )(input)
+pub fn parse_comment(input: &str) -> Option<(&str, &str)> {
+    let (input, content) = take_lines_while(|line| line == "#" || line.starts_with("# "))(input);
+
+    if !content.is_empty() {
+        Some((input, content))
+    } else {
+        None
+    }
 }
 
-pub fn take_one_word(input: &str) -> IResult<&str, &str> {
+pub fn take_one_word<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, &'a str, E> {
     take_while1(|c: char| !c.is_ascii_whitespace())(input)
 }