use std::borrow::Cow; use anyhow::{anyhow, Result}; use helix_core::{smallvec, SmallVec, Tendril}; #[derive(Debug, PartialEq, Eq)] pub enum CaseChange { Upcase, Downcase, Capitalize, } #[derive(Debug, PartialEq, Eq)] pub enum FormatItem<'a> { Text(Tendril), Capture(usize), CaseChange(usize, CaseChange), Conditional(usize, Option<&'a str>, Option<&'a str>), } #[derive(Debug, PartialEq, Eq)] pub struct Regex<'a> { value: Tendril, replacement: Vec>, options: Tendril, } #[derive(Debug, PartialEq, Eq)] pub enum SnippetElement<'a> { Tabstop { tabstop: usize, }, Placeholder { tabstop: usize, value: Vec>, }, Choice { tabstop: usize, choices: Vec, }, Variable { name: &'a str, default: Option<&'a str>, regex: Option>, }, Text(Tendril), } #[derive(Debug, PartialEq, Eq)] pub struct Snippet<'a> { elements: Vec>, } pub fn parse(s: &str) -> Result> { parser::parse(s).map_err(|rest| anyhow!("Failed to parse snippet. Remaining input: {}", rest)) } fn render_elements( snippet_elements: &[SnippetElement<'_>], insert: &mut Tendril, offset: &mut usize, tabstops: &mut Vec<(usize, (usize, usize))>, newline_with_offset: &str, include_placeholer: bool, ) { use SnippetElement::*; for element in snippet_elements { match element { 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.as_str()) }; *offset += text.chars().count(); insert.push_str(&text); } &Variable { name: _, regex: _, r#default, } => { // TODO: variables. For now, fall back to the default, which defaults to "". let text = r#default.unwrap_or_default(); *offset += text.chars().count(); insert.push_str(text); } &Tabstop { tabstop } => { tabstops.push((tabstop, (*offset, *offset))); } Placeholder { tabstop, value: inner_snippet_elements, } => { let start_offset = *offset; if include_placeholer { render_elements( inner_snippet_elements, insert, offset, tabstops, newline_with_offset, include_placeholer, ); } tabstops.push((*tabstop, (start_offset, *offset))); } &Choice { tabstop, choices: _, } => { // TODO: choices tabstops.push((tabstop, (*offset, *offset))); } } } } #[allow(clippy::type_complexity)] // only used one time pub fn render( snippet: &Snippet<'_>, newline_with_offset: &str, include_placeholer: bool, ) -> (Tendril, Vec>) { let mut insert = Tendril::new(); let mut tabstops = Vec::new(); let mut offset = 0; render_elements( &snippet.elements, &mut insert, &mut offset, &mut tabstops, newline_with_offset, include_placeholer, ); // sort in ascending order (except for 0, which should always be the last one (per lsp doc)) tabstops.sort_unstable_by_key(|(n, _)| if *n == 0 { usize::MAX } else { *n }); // merge tabstops with the same index (we take advantage of the fact that we just sorted them // above to simply look backwards) let mut ntabstops = Vec::>::new(); { let mut prev = None; for (tabstop, r) in tabstops { if prev == Some(tabstop) { let len_1 = ntabstops.len() - 1; ntabstops[len_1].push(r); } else { prev = Some(tabstop); ntabstops.push(smallvec![r]); } } } (insert, ntabstops) } mod parser { use helix_core::Tendril; use helix_parsec::*; use super::{CaseChange, FormatItem, Regex, Snippet, SnippetElement}; /* https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#snippet_syntax any ::= tabstop | placeholder | choice | variable | text tabstop ::= '$' int | '${' int '}' placeholder ::= '${' int ':' any '}' choice ::= '${' int '|' text (',' text)* '|}' variable ::= '$' var | '${' var }' | '${' var ':' any '}' | '${' var '/' regex '/' (format | text)+ '/' options '}' format ::= '$' int | '${' int '}' | '${' int ':' '/upcase' | '/downcase' | '/capitalize' '}' | '${' int ':+' if '}' | '${' int ':?' if ':' else '}' | '${' int ':-' else '}' | '${' int ':' else '}' regex ::= Regular Expression value (ctor-string) options ::= Regular Expression option (ctor-options) var ::= [_a-zA-Z] [_a-zA-Z0-9]* int ::= [0-9]+ text ::= .* if ::= text else ::= text */ fn var<'a>() -> impl Parser<'a, Output = &'a str> { // var = [_a-zA-Z][_a-zA-Z0-9]* move |input: &'a str| match input .char_indices() .take_while(|(p, c)| { *c == '_' || if *p == 0 { c.is_ascii_alphabetic() } else { c.is_ascii_alphanumeric() } }) .last() { Some((index, c)) if index >= 1 => { let index = index + c.len_utf8(); Ok((&input[index..], &input[0..index])) } _ => Err(input), } } const TEXT_ESCAPE_CHARS: &[char] = &['\\', '}', '$']; 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> { filter_map(take_while(|c| c.is_ascii_digit()), |s| s.parse().ok()) } fn case_change<'a>() -> impl Parser<'a, Output = CaseChange> { use CaseChange::*; choice!( map("upcase", |_| Upcase), map("downcase", |_| Downcase), map("capitalize", |_| Capitalize), ) } fn format<'a>() -> impl Parser<'a, Output = FormatItem<'a>> { use FormatItem::*; choice!( // '$' int map(right("$", digit()), Capture), // '${' int '}' map(seq!("${", digit(), "}"), |seq| Capture(seq.1)), // '${' int ':' '/upcase' | '/downcase' | '/capitalize' '}' map(seq!("${", digit(), ":/", case_change(), "}"), |seq| { CaseChange(seq.1, seq.3) }), // '${' int ':+' if '}' map( seq!("${", digit(), ":+", take_until(|c| c == '}'), "}"), |seq| { Conditional(seq.1, Some(seq.3), None) } ), // '${' int ':?' if ':' else '}' map( seq!( "${", digit(), ":?", take_until(|c| c == ':'), ":", take_until(|c| c == '}'), "}" ), |seq| { Conditional(seq.1, Some(seq.3), Some(seq.5)) } ), // '${' int ':-' else '}' | '${' int ':' else '}' map( seq!( "${", digit(), ":", optional("-"), take_until(|c| c == '}'), "}" ), |seq| { Conditional(seq.1, None, Some(seq.4)) } ), ) } fn regex<'a>() -> impl Parser<'a, Output = Regex<'a>> { map( seq!( "/", // TODO parse as ECMAScript and convert to rust regex non_empty(text(&['/', '\\'])), "/", one_or_more(choice!( format(), map(text(REPLACE_ESCAPE_CHARS), FormatItem::Text) )), "/", text(&['}', '\\',]), ), |(_, value, _, replacement, _, options)| Regex { value, replacement, options, }, ) } fn tabstop<'a>() -> impl Parser<'a, Output = SnippetElement<'a>> { map( or( right("$", digit()), map(seq!("${", digit(), "}"), |values| values.1), ), |digit| SnippetElement::Tabstop { tabstop: digit }, ) } fn placeholder<'a>() -> impl Parser<'a, Output = SnippetElement<'a>> { map( seq!( "${", digit(), ":", // according to the grammar there is just a single anything here. // However in the prose it is explained that placeholders can be nested. // The example there contains both a placeholder text and a nested placeholder // which indicates a list. Looking at the VSCode sourcecode, the placeholder // is indeed parsed as zero_or_more so the grammar is simply incorrect here zero_or_more(anything(TEXT_ESCAPE_CHARS)), "}" ), |seq| SnippetElement::Placeholder { tabstop: seq.1, value: seq.3, }, ) } fn choice<'a>() -> impl Parser<'a, Output = SnippetElement<'a>> { map( seq!( "${", digit(), "|", sep(text(CHOICE_TEXT_ESCAPE_CHARS), ","), "|}", ), |seq| SnippetElement::Choice { tabstop: seq.1, choices: seq.3, }, ) } fn variable<'a>() -> impl Parser<'a, Output = SnippetElement<'a>> { choice!( // $var map(right("$", var()), |name| SnippetElement::Variable { name, default: None, regex: None, }), // ${var:default} map( seq!("${", var(), ":", take_until(|c| c == '}'), "}",), |values| SnippetElement::Variable { name: values.1, default: Some(values.3), regex: None, } ), // ${var/value/format/options} map(seq!("${", var(), regex(), "}"), |values| { SnippetElement::Variable { name: values.1, default: None, regex: Some(values.2), } }), ) } 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>> { map(one_or_more(anything(TEXT_ESCAPE_CHARS)), |parts| Snippet { elements: parts, }) } pub fn parse(s: &str) -> Result { snippet().parse(s).and_then(|(remainder, snippet)| { if remainder.is_empty() { Ok(snippet) } else { Err(remainder) } }) } #[cfg(test)] mod test { use super::SnippetElement::*; use super::*; #[test] fn empty_string_is_error() { assert_eq!(Err(""), parse("")); } #[test] fn parse_placeholders_in_function_call() { assert_eq!( Ok(Snippet { elements: vec![ Text("match(".into()), Placeholder { tabstop: 1, value: vec!(Text("Arg1".into())), }, Text(")".into()) ] }), parse("match(${1:Arg1})") ) } #[test] fn parse_unterminated_placeholder_error() { assert_eq!(Err("${1:)"), parse("match(${1:)")) } #[test] fn parse_empty_placeholder() { assert_eq!( Ok(Snippet { elements: vec![ Text("match(".into()), Placeholder { tabstop: 1, value: vec![], }, Text(")".into()) ] }), parse("match(${1:})") ) } #[test] fn parse_placeholders_in_statement() { assert_eq!( Ok(Snippet { elements: vec![ Text("local ".into()), Placeholder { tabstop: 1, value: vec!(Text("var".into())), }, Text(" = ".into()), Placeholder { tabstop: 1, value: vec!(Text("value".into())), }, ] }), parse("local ${1:var} = ${1:value}") ) } #[test] fn parse_tabstop_nested_in_placeholder() { assert_eq!( Ok(Snippet { elements: vec![Placeholder { tabstop: 1, value: vec!(Text("var, ".into()), Tabstop { tabstop: 2 },), },] }), parse("${1:var, $2}") ) } #[test] fn parse_placeholder_nested_in_placeholder() { assert_eq!( Ok(Snippet { elements: vec![Placeholder { tabstop: 1, value: vec!( Text("foo ".into()), Placeholder { tabstop: 2, value: vec!(Text("bar".into())), }, ), },] }), parse("${1:foo ${2:bar}}") ) } #[test] fn parse_all() { assert_eq!( Ok(Snippet { elements: vec![ Text("hello ".into()), Tabstop { tabstop: 1 }, Tabstop { tabstop: 2 }, Text(" ".into()), Choice { tabstop: 1, choices: vec!["one".into(), "two".into(), "three".into()] }, Text(" ".into()), Variable { name: "name", default: Some("foo"), regex: None }, Text(" ".into()), Variable { name: "var", default: None, regex: None }, Text(" ".into()), Variable { name: "TM", default: None, regex: None }, ] }), parse("hello $1${2} ${1|one,two,three|} ${name:foo} $var $TM") ); } #[test] fn regex_capture_replace() { assert_eq!( Ok(Snippet { elements: vec![Variable { name: "TM_FILENAME", default: None, regex: Some(Regex { value: "(.*).+$".into(), replacement: vec![FormatItem::Capture(1)], options: Tendril::new(), }), }] }), parse("${TM_FILENAME/(.*).+$/$1/}") ); } } }