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git-config/src/parser.rs

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2021-02-18 09:49:47 -08:00
use crate::values::{Boolean, TrueVariant, Value};
use nom::bytes::complete::{escaped, tag, take_till, take_while};
use nom::character::complete::{char, none_of, one_of};
use nom::character::{is_newline, is_space};
use nom::combinator::{map, opt};
use nom::error::{Error as NomError, ErrorKind};
use nom::multi::many1;
use nom::sequence::delimited;
use nom::IResult;
use nom::{branch::alt, multi::many0};
/// An event is any syntactic event that occurs in the config.
#[derive(PartialEq, Debug)]
pub enum Event<'a> {
Comment(Comment<'a>),
Key(&'a str),
/// Represents any token used to signify a new line character. On Unix
/// platforms, this is typically just `\n`, but can be any valid newline
/// sequence.
Newline(&'a str),
///
Value(Value<'a>),
/// Any value that isn't completed. This occurs when the value is continued
/// onto the next line. A Newline event is guaranteed after, followed by
/// either another ValueNotDone or a ValueDone.
ValueNotDone(&'a str),
/// The last line of a value which was continued onto another line.
ValueDone(&'a str),
}
#[derive(PartialEq, Debug)]
pub struct Section<'a> {
section_header: SectionHeader<'a>,
items: Vec<Event<'a>>,
}
#[derive(PartialEq, Debug)]
pub struct SectionHeader<'a> {
name: &'a str,
subsection_name: Option<&'a str>,
}
#[derive(PartialEq, Debug)]
pub struct Comment<'a> {
comment_tag: char,
comment: &'a str,
}
pub struct Parser<'a> {
init_comments: Vec<Comment<'a>>,
sections: Vec<Section<'a>>,
}
pub fn parse(input: &str) -> Result<Parser<'_>, ()> {
let (i, comments) = many0(comment)(input).unwrap();
let (i, sections) = many1(section)(i).unwrap();
Ok(Parser {
init_comments: comments,
sections,
})
}
fn comment<'a>(i: &'a str) -> IResult<&'a str, Comment<'a>> {
let i = i.trim_start();
let (i, comment_tag) = one_of(";#")(i)?;
let (i, comment) = take_till(is_char_newline)(i)?;
Ok((
i,
Comment {
comment_tag,
comment,
},
))
}
fn section<'a>(i: &'a str) -> IResult<&'a str, Section<'a>> {
let (i, section_header) = section_header(i)?;
// need alt here for eof?
let (i, items) = many1(alt((
map(section_body, |(key, values)| {
let mut vec = vec![Event::Key(key)];
vec.extend(values);
vec
}),
map(comment, |comment| vec![Event::Comment(comment)]),
)))(i)?;
Ok((
i,
Section {
section_header,
items: items.into_iter().flatten().collect(),
},
))
}
fn section_header<'a>(i: &'a str) -> IResult<&'a str, SectionHeader<'a>> {
let (i, _) = char('[')(i)?;
// No spaces must be between section name and section start
let (i, name) = take_while(|c: char| c.is_ascii_alphanumeric() || c == '-' || c == '.')(i)?;
if let Ok((i, _)) = char::<_, NomError<&str>>(']')(i) {
// Either section does not have a subsection or using deprecated
// subsection syntax at this point.
let header = match name.rfind('.') {
Some(index) => SectionHeader {
name: &name[..index],
subsection_name: Some(&name[index + 1..]),
},
None => SectionHeader {
name: name,
subsection_name: None,
},
};
return Ok((i, header));
}
// Section header must be using modern subsection syntax at this point.
let (i, _) = take_spaces(i)?;
let (i, subsection_name) = delimited(
char('"'),
opt(escaped(none_of("\"\\\n\0"), '\\', one_of(r#""\"#))),
tag("\"]"),
)(i)?;
Ok((
i,
SectionHeader {
name: name,
// We know that there's some section name here, so if we get an
// empty vec here then we actually parsed an empty section name.
subsection_name: subsection_name.or(Some("")),
},
))
}
fn take_spaces<'a>(i: &'a str) -> IResult<&'a str, &'a str> {
take_while(|c: char| c.is_ascii() && is_space(c as u8))(i)
}
fn section_body<'a>(i: &'a str) -> IResult<&'a str, (&'a str, Vec<Event<'a>>)> {
let i = i.trim_start();
// maybe need to check for [ here
let (i, name) = config_name(i)?;
let (i, _) = take_spaces(i)?;
let (i, value) = config_value(i)?;
Ok((i, (name, value)))
}
/// Parses the config name of a config pair. Assumes the input has already been
/// trimmed of any leading whitespace.
fn config_name<'a>(i: &'a str) -> IResult<&'a str, &'a str> {
if i.is_empty() {
return Err(nom::Err::Error(NomError {
input: i,
code: ErrorKind::NonEmpty,
}));
}
if !i.chars().nth(0).unwrap().is_alphabetic() {
return Err(nom::Err::Error(NomError {
input: i,
code: ErrorKind::Alpha,
}));
}
take_while(|c: char| c.is_alphanumeric() || c == '-')(i)
}
fn config_value<'a>(i: &'a str) -> IResult<&'a str, Vec<Event<'a>>> {
if let (i, Some(_)) = opt(char('='))(i)? {
let (i, _) = take_spaces(i)?;
value_impl(i)
} else {
Ok((
i,
vec![Event::Value(Value::Boolean(Boolean::True(
TrueVariant::Implicit,
)))],
))
}
}
fn value_impl<'a>(i: &'a str) -> IResult<&'a str, Vec<Event<'a>>> {
// I wrote this code and don't know how it works.
//
// Even after sleeping on it I still don't know how it works.
let mut events = vec![];
let mut parsed_index: usize = 0;
let mut offset: usize = 0;
let mut was_prev_char_escape_char = false;
// This is required to ignore comment markers if they're in a quote.
let mut is_in_quotes = false;
// Used to determine if we return a Value or Value{Not,}Done
let mut partial_value_found = false;
for (index, c) in i.as_bytes().iter().enumerate() {
if was_prev_char_escape_char {
was_prev_char_escape_char = false;
match c {
// We're escaping a newline, which means we've found a
// continuation.
b'\n' => {
partial_value_found = true;
events.push(Event::ValueNotDone(&i[offset..index - 1]));
events.push(Event::Newline(&i[index..index + 1]));
offset = index + 1;
parsed_index = 0;
}
b't' | b'\\' | b'n' | b'"' => (),
_ => {
return Err(nom::Err::Error(NomError {
input: i,
code: ErrorKind::Escaped,
}));
}
}
} else {
match c {
b'\n' => {
parsed_index = index;
break;
}
b';' | b'#' if !is_in_quotes => {
parsed_index = index;
break;
}
b'\\' => was_prev_char_escape_char = true,
b'"' => is_in_quotes = !is_in_quotes,
_ => {}
}
}
}
if parsed_index == 0 {
parsed_index = i.len();
}
// Handle incomplete escape
if was_prev_char_escape_char {
return Err(nom::Err::Error(NomError {
input: i,
code: ErrorKind::Escaped,
}));
}
// Handle incomplete quotes
if is_in_quotes {
return Err(nom::Err::Error(NomError {
input: i,
code: ErrorKind::Tag,
}));
}
let remainder_value = &i[offset..parsed_index].trim_end();
if partial_value_found {
events.push(Event::ValueDone(remainder_value));
} else {
events.push(Event::Value(Value::from_str(remainder_value)));
}
Ok((&i[parsed_index..], events))
}
fn is_char_newline(c: char) -> bool {
c.is_ascii() && is_newline(c as u8)
}
#[cfg(test)]
mod parse {
use super::*;
fn fully_consumed<T>(t: T) -> (&'static str, T) {
("", t)
}
mod comments {
use super::super::*;
use super::*;
#[test]
fn semicolon() {
assert_eq!(
comment("; this is a semicolon comment").unwrap(),
fully_consumed(Comment {
comment_tag: ';',
comment: " this is a semicolon comment",
})
);
}
#[test]
fn octothorpe() {
assert_eq!(
comment("# this is an octothorpe comment").unwrap(),
fully_consumed(Comment {
comment_tag: '#',
comment: " this is an octothorpe comment",
})
);
}
#[test]
fn multiple_markers() {
assert_eq!(
comment("###### this is an octothorpe comment").unwrap(),
fully_consumed(Comment {
comment_tag: '#',
comment: "##### this is an octothorpe comment",
})
);
}
}
mod section_headers {
use super::super::*;
use super::*;
#[test]
fn no_subsection() {
assert_eq!(
section_header("[hello]").unwrap(),
fully_consumed(SectionHeader {
name: "hello",
subsection_name: None
})
);
}
#[test]
fn modern_subsection() {
assert_eq!(
section_header(r#"[hello "world"]"#).unwrap(),
fully_consumed(SectionHeader {
name: "hello",
subsection_name: Some("world")
})
);
}
#[test]
fn escaped_subsection() {
assert_eq!(
section_header(r#"[hello "foo\\bar\""]"#).unwrap(),
fully_consumed(SectionHeader {
name: "hello",
subsection_name: Some(r#"foo\\bar\""#)
})
);
}
#[test]
fn deprecated_subsection() {
assert_eq!(
section_header(r#"[hello.world]"#).unwrap(),
fully_consumed(SectionHeader {
name: "hello",
subsection_name: Some("world")
})
);
}
#[test]
fn empty_legacy_subsection_name() {
assert_eq!(
section_header(r#"[hello.]"#).unwrap(),
fully_consumed(SectionHeader {
name: "hello",
subsection_name: Some("")
})
);
}
#[test]
fn empty_modern_subsection_name() {
assert_eq!(
section_header(r#"[hello ""]"#).unwrap(),
fully_consumed(SectionHeader {
name: "hello",
subsection_name: Some("")
})
);
}
#[test]
fn newline_in_header() {
assert!(section_header("[hello\n]").is_err())
}
#[test]
fn null_byte_in_header() {
assert!(section_header("[hello\0]").is_err())
}
#[test]
fn right_brace_in_subsection_name() {
assert_eq!(
section_header(r#"[hello "]"]"#).unwrap(),
fully_consumed(SectionHeader {
name: "hello",
subsection_name: Some("]")
})
);
}
}
mod config_name {
use super::super::*;
use super::*;
#[test]
fn just_name() {
assert_eq!(config_name("name").unwrap(), fully_consumed("name"));
}
#[test]
fn must_start_with_alphabetic() {
assert!(config_name("4aaa").is_err());
assert!(config_name("-aaa").is_err());
}
#[test]
fn cannot_be_empty() {
assert!(config_name("").is_err())
}
}
mod value_no_continuation {
use super::super::*;
use super::*;
#[test]
fn no_comment() {
assert_eq!(
value_impl("hello").unwrap(),
fully_consumed(vec![Event::Value(Value::Other("hello"))])
);
}
#[test]
fn no_comment_newline() {
assert_eq!(
value_impl("hello\na").unwrap(),
("\na", vec![Event::Value(Value::Other("hello"))])
)
}
#[test]
fn no_comment_is_trimmed() {
assert_eq!(
value_impl("hello").unwrap(),
value_impl("hello ").unwrap()
);
}
#[test]
fn semicolon_comment_not_consumed() {
assert_eq!(
value_impl("hello;world").unwrap(),
(";world", vec![Event::Value(Value::Other("hello")),])
);
}
#[test]
fn octothorpe_comment_not_consumed() {
assert_eq!(
value_impl("hello#world").unwrap(),
("#world", vec![Event::Value(Value::Other("hello")),])
);
}
#[test]
fn values_with_comments_are_trimmed() {
assert_eq!(
value_impl("hello#world").unwrap(),
value_impl("hello #world").unwrap(),
);
assert_eq!(
value_impl("hello;world").unwrap(),
value_impl("hello ;world").unwrap(),
);
}
#[test]
fn trans_escaped_comment_marker_not_consumed() {
assert_eq!(
value_impl(r##"hello"#"world; a"##).unwrap(),
(
"; a",
vec![Event::Value(Value::Other(r##"hello"#"world"##)),]
)
);
}
#[test]
fn complex_test() {
assert_eq!(
value_impl(r#"value";";ahhhh"#).unwrap(),
(";ahhhh", vec![Event::Value(Value::Other(r#"value";""#)),])
);
}
#[test]
fn garbage_after_continution_is_err() {
assert!(value_impl("hello \\afwjdls").is_err());
}
}
mod value_continuation {
use super::super::*;
use super::*;
#[test]
fn simple_continuation() {
assert_eq!(
value_impl("hello\\\nworld").unwrap(),
fully_consumed(vec![
Event::ValueNotDone("hello"),
Event::Newline("\n"),
Event::ValueDone("world")
])
);
}
#[test]
fn complex_continuation_with_leftover_comment() {
assert_eq!(
value_impl("1 \"\\\"\\\na ; e \"\\\"\\\nd # \"b\t ; c").unwrap(),
(
"# \"b\t ; c",
vec![
Event::ValueNotDone(r#"1 "\""#),
Event::Newline("\n"),
Event::ValueNotDone(r#"a ; e "\""#),
Event::Newline("\n"),
Event::ValueDone("d"),
]
)
);
}
#[test]
fn quote_split_over_two_lines_with_leftover_comment() {
assert_eq!(
value_impl("\"\\\n;\";a").unwrap(),
(
";a",
vec![
Event::ValueNotDone("\""),
Event::Newline("\n"),
Event::ValueDone(";\""),
]
)
)
}
}
mod section {
use super::super::*;
use super::*;
#[test]
fn simple_section() {
let section_data = r#"[hello]
a = b
c
d = "lol""#;
assert_eq!(
section(section_data).unwrap(),
fully_consumed(Section {
section_header: SectionHeader {
name: "hello",
subsection_name: None,
},
items: vec![
Event::Key("a"),
Event::Value(Value::from_str("b")),
Event::Key("c"),
Event::Value(Value::Boolean(Boolean::True(TrueVariant::Implicit))),
Event::Key("d"),
Event::Value(Value::from_str("\"lol\""))
]
})
)
}
#[test]
fn section_single_line() {
assert_eq!(
section("[hello] c").unwrap(),
fully_consumed(Section {
section_header: SectionHeader {
name: "hello",
subsection_name: None,
},
items: vec![
Event::Key("c"),
Event::Value(Value::Boolean(Boolean::True(TrueVariant::Implicit)))
]
})
);
}
#[test]
fn section_very_commented() {
let section_data = r#"[hello] ; commentA
a = b # commentB
; commentC
; commentD
c = d"#;
assert_eq!(
section(section_data).unwrap(),
fully_consumed(Section {
section_header: SectionHeader {
name: "hello",
subsection_name: None,
},
items: vec![
Event::Comment(Comment {
comment_tag: ';',
comment: " commentA",
}),
Event::Key("a"),
Event::Value(Value::from_str("b")),
Event::Comment(Comment {
comment_tag: '#',
comment: " commentB",
}),
Event::Comment(Comment {
comment_tag: ';',
comment: " commentC",
}),
Event::Comment(Comment {
comment_tag: ';',
comment: " commentD",
}),
Event::Key("c"),
Event::Value(Value::from_str("d")),
]
})
);
}
#[test]
fn complex_continuation() {
// This test is absolute hell. Good luck if this fails.
assert_eq!(
section("[section] a = 1 \"\\\"\\\na ; e \"\\\"\\\nd # \"b\t ; c").unwrap(),
fully_consumed(Section {
section_header: SectionHeader {
name: "section",
subsection_name: None,
},
items: vec![
Event::Key("a"),
Event::ValueNotDone(r#"1 "\""#),
Event::Newline("\n"),
Event::ValueNotDone(r#"a ; e "\""#),
Event::Newline("\n"),
Event::ValueDone("d"),
Event::Comment(Comment {
comment_tag: '#',
comment: " \"b\t ; c"
})
]
})
);
}
#[test]
fn quote_split_over_two_lines() {
assert_eq!(
section("[section \"a\"] b =\"\\\n;\";a").unwrap(),
fully_consumed(Section {
section_header: SectionHeader {
name: "section",
subsection_name: Some("a")
},
items: vec![
Event::Key("b"),
Event::ValueNotDone("\""),
Event::Newline("\n"),
Event::ValueDone(";\""),
Event::Comment(Comment {
comment: "a",
comment_tag: ';'
})
]
})
)
}
}
}