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revamped snippet text element parsing
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Snippet text elements can contain escape sequences
that must be treated properly. Furthermore snippets
must always escape certain characters (like `}`
or `\`). The function has been updated to account
for that. `text` is now also included with
`anything` to match the grammar and can also
match empty text. To avoid infinite loops the
`non-empty` combinator has been added which is
automatically used in the `one_or_more` and
`zero_or more` combinator where the problemn would
occur.
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@pascalkuthe @archseer
pascalkuthe authored and archseer committed Mar 16, 2023
1 parent bbf4800 commit 90348b8
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Showing 2 changed files with 85 additions and 45 deletions.
117 changes: 72 additions & 45 deletions helix-lsp/src/snippet.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,17 +12,17 @@ pub enum CaseChange {

#[derive(Debug, PartialEq, Eq)]
pub enum FormatItem<'a> {
Text(&'a str),
Text(Tendril),
Capture(usize),
CaseChange(usize, CaseChange),
Conditional(usize, Option<&'a str>, Option<&'a str>),
}

#[derive(Debug, PartialEq, Eq)]
pub struct Regex<'a> {
value: &'a str,
value: Tendril,
replacement: Vec<FormatItem<'a>>,
options: Option<&'a str>,
options: Tendril,
}

#[derive(Debug, PartialEq, Eq)]
Expand All @@ -36,14 +36,14 @@ pub enum SnippetElement<'a> {
},
Choice {
tabstop: usize,
choices: Vec<&'a str>,
choices: Vec<Tendril>,
},
Variable {
name: &'a str,
default: Option<&'a str>,
regex: Option<Regex<'a>>,
},
Text(&'a str),
Text(Tendril),
}

#[derive(Debug, PartialEq, Eq)]
Expand All @@ -67,12 +67,12 @@ fn render_elements(

for element in snippet_elements {
match element {
&Text(text) => {
Text(text) => {
// small optimization to avoid calling replace when it's unnecessary
let text = if text.contains('\n') {
Cow::Owned(text.replace('\n', newline_with_offset))
} else {
Cow::Borrowed(text)
Cow::Borrowed(text.as_str())
};
*offset += text.chars().count();
insert.push_str(&text);
Expand Down Expand Up @@ -160,6 +160,7 @@ pub fn render(
}

mod parser {
use helix_core::Tendril;
use helix_parsec::*;

use super::{CaseChange, FormatItem, Regex, Snippet, SnippetElement};
Expand Down Expand Up @@ -210,8 +211,32 @@ mod parser {
}
}

fn text<'a, const SIZE: usize>(cs: [char; SIZE]) -> impl Parser<'a, Output = &'a str> {
take_while(move |c| cs.into_iter().all(|c1| c != c1))
const TEXT_ESCAPE_CHARS: &[char] = &['\\', '}', '$'];
const REPLACE_ESCAPE_CHARS: &[char] = &['\\', '}', '$', '/'];
const CHOICE_TEXT_ESCAPE_CHARS: &[char] = &['\\', '}', '$', '|', ','];

fn text<'a>(escape_chars: &'static [char]) -> impl Parser<'a, Output = Tendril> {
move |input: &'a str| {
let mut chars = input.char_indices();
let mut res = Tendril::new();
while let Some((i, c)) = chars.next() {
match c {
'\\' => {
if let Some((_, c)) = chars.next() {
if escape_chars.contains(&c) {
res.push(c);
continue;
}
}
return Ok((&input[i..], res));
}
c if escape_chars.contains(&c) => return Ok((&input[i..], res)),
c => res.push(c),
}
}

Ok(("", res))
}
}

fn digit<'a>() -> impl Parser<'a, Output = usize> {
Expand Down Expand Up @@ -274,20 +299,18 @@ mod parser {
}

fn regex<'a>() -> impl Parser<'a, Output = Regex<'a>> {
let text = map(text(['$', '/']), FormatItem::Text);
let replacement = reparse_as(
take_until(|c| c == '/'),
one_or_more(choice!(format(), text)),
);

map(
seq!(
"/",
take_until(|c| c == '/'),
// TODO parse as ECMAScript and convert to rust regex
non_empty(text(&['/', '\\'])),
"/",
replacement,
one_or_more(choice!(
format(),
map(text(REPLACE_ESCAPE_CHARS), FormatItem::Text)
)),
"/",
optional(take_until(|c| c == '}')),
text(&['}', '\\',]),
),
|(_, value, _, replacement, _, options)| Regex {
value,
Expand All @@ -308,13 +331,12 @@ mod parser {
}

fn placeholder<'a>() -> impl Parser<'a, Output = SnippetElement<'a>> {
let text = map(text(['$', '}']), SnippetElement::Text);
map(
seq!(
"${",
digit(),
":",
one_or_more(choice!(anything(), text)),
one_or_more(anything(TEXT_ESCAPE_CHARS)),
"}"
),
|seq| SnippetElement::Placeholder {
Expand All @@ -330,7 +352,7 @@ mod parser {
"${",
digit(),
"|",
sep(take_until(|c| c == ',' || c == '|'), ","),
sep(text(CHOICE_TEXT_ESCAPE_CHARS), ","),
"|}",
),
|seq| SnippetElement::Choice {
Expand Down Expand Up @@ -368,17 +390,21 @@ mod parser {
)
}

fn anything<'a>() -> impl Parser<'a, Output = SnippetElement<'a>> {
// The parser has to be constructed lazily to avoid infinite opaque type recursion
|input: &'a str| {
let parser = choice!(tabstop(), placeholder(), choice(), variable());
fn anything<'a>(escape_chars: &'static [char]) -> impl Parser<'a, Output = SnippetElement<'a>> {
move |input: &'a str| {
let parser = choice!(
tabstop(),
placeholder(),
choice(),
variable(),
map(text(escape_chars), SnippetElement::Text)
);
parser.parse(input)
}
}

fn snippet<'a>() -> impl Parser<'a, Output = Snippet<'a>> {
let text = map(text(['$']), SnippetElement::Text);
map(one_or_more(choice!(anything(), text)), |parts| Snippet {
map(one_or_more(anything(TEXT_ESCAPE_CHARS)), |parts| Snippet {
elements: parts,
})
}
Expand All @@ -392,6 +418,7 @@ mod parser {
}
})
}

#[cfg(test)]
mod test {
use super::SnippetElement::*;
Expand All @@ -407,12 +434,12 @@ mod parser {
assert_eq!(
Ok(Snippet {
elements: vec![
Text("match("),
Text("match(".into()),
Placeholder {
tabstop: 1,
value: vec!(Text("Arg1")),
value: vec!(Text("Arg1".into())),
},
Text(")")
Text(")".into())
]
}),
parse("match(${1:Arg1})")
Expand Down Expand Up @@ -446,15 +473,15 @@ mod parser {
assert_eq!(
Ok(Snippet {
elements: vec![
Text("local "),
Text("local ".into()),
Placeholder {
tabstop: 1,
value: vec!(Text("var")),
value: vec!(Text("var".into())),
},
Text(" = "),
Text(" = ".into()),
Placeholder {
tabstop: 1,
value: vec!(Text("value")),
value: vec!(Text("value".into())),
},
]
}),
Expand All @@ -468,7 +495,7 @@ mod parser {
Ok(Snippet {
elements: vec![Placeholder {
tabstop: 1,
value: vec!(Text("var, "), Tabstop { tabstop: 2 },),
value: vec!(Text("var, ".into()), Tabstop { tabstop: 2 },),
},]
}),
parse("${1:var, $2}")
Expand All @@ -482,10 +509,10 @@ mod parser {
elements: vec![Placeholder {
tabstop: 1,
value: vec!(
Text("foo "),
Text("foo ".into()),
Placeholder {
tabstop: 2,
value: vec!(Text("bar")),
value: vec!(Text("bar".into())),
},
),
},]
Expand All @@ -499,27 +526,27 @@ mod parser {
assert_eq!(
Ok(Snippet {
elements: vec![
Text("hello "),
Text("hello ".into()),
Tabstop { tabstop: 1 },
Tabstop { tabstop: 2 },
Text(" "),
Text(" ".into()),
Choice {
tabstop: 1,
choices: vec!["one", "two", "three"]
choices: vec!["one".into(), "two".into(), "three".into()]
},
Text(" "),
Text(" ".into()),
Variable {
name: "name",
default: Some("foo"),
regex: None
},
Text(" "),
Text(" ".into()),
Variable {
name: "var",
default: None,
regex: None
},
Text(" "),
Text(" ".into()),
Variable {
name: "TM",
default: None,
Expand All @@ -539,9 +566,9 @@ mod parser {
name: "TM_FILENAME",
default: None,
regex: Some(Regex {
value: "(.*).+$",
value: "(.*).+$".into(),
replacement: vec![FormatItem::Capture(1)],
options: None,
options: Tendril::new(),
}),
}]
}),
Expand Down
13 changes: 13 additions & 0 deletions helix-parsec/src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -459,6 +459,7 @@ pub fn zero_or_more<'a, P, T>(parser: P) -> impl Parser<'a, Output = Vec<T>>
where
P: Parser<'a, Output = T>,
{
let parser = non_empty(parser);
move |mut input| {
let mut values = Vec::new();

Expand Down Expand Up @@ -491,6 +492,7 @@ pub fn one_or_more<'a, P, T>(parser: P) -> impl Parser<'a, Output = Vec<T>>
where
P: Parser<'a, Output = T>,
{
let parser = non_empty(parser);
move |mut input| {
let mut values = Vec::new();

Expand Down Expand Up @@ -559,3 +561,14 @@ where
Ok((input, values))
}
}

pub fn non_empty<'a, T>(p: impl Parser<'a, Output = T>) -> impl Parser<'a, Output = T> {
move |input| {
let (new_input, res) = p.parse(input)?;
if new_input.len() == input.len() {
Err(input)
} else {
Ok((new_input, res))
}
}
}

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