git.delta.rocks / jrsonnet / refs/commits / d32a788bb470

1#[derive(Clone, Copy, Debug, PartialEq, Eq)]2pub enum StringBlockError {3	UnexpectedEnd,4	MissingNewLine,5	MissingTermination,6	MissingIndent,7}89use std::ops::Range;1011use logos::Lexer;12use StringBlockError::*;1314use crate::SyntaxKind;1516pub fn lex_str_block_test(lex: &mut Lexer<SyntaxKind>) {17	let _ = lex_str_block(lex);18}1920#[allow(clippy::too_many_lines)]21pub fn lex_str_block(lex: &mut Lexer<SyntaxKind>) -> Result<(), StringBlockError> {22	struct Context<'a> {23		source: &'a str,24		index: usize,25		offset: usize,26	}2728	impl<'a> Context<'a> {29		fn rest(&self) -> &'a str {30			&self.source[self.index..]31		}3233		fn next(&mut self) -> Option<char> {34			if self.index == self.source.len() {35				return None;36			}3738			match self.rest().chars().next() {39				None => None,40				Some(c) => {41					self.index += c.len_utf8();42					Some(c)43				}44			}45		}4647		fn peek(&self) -> Option<char> {48			if self.index == self.source.len() {49				return None;50			}5152			self.rest().chars().next()53		}5455		fn eat_if(&mut self, f: impl Fn(char) -> bool) -> usize {56			if self.peek().map(f).unwrap_or(false) {57				self.index += 1;58				return 1;59			}60			061		}6263		fn eat_while(&mut self, f: impl Fn(char) -> bool) -> usize {64			if self.index == self.source.len() {65				return 0;66			}6768			let next_char = self.rest().char_indices().find(|(_, c)| !f(*c));6970			match next_char {71				None => {72					let diff = self.source.len() - self.index;73					self.index = self.source.len();74					diff75				}76				Some((idx, _)) => {77					self.index += idx;78					idx79				}80			}81		}8283		fn skip(&mut self, len: usize) {84			self.index = match self.index + len {85				n if n > self.source.len() => self.source.len(),86				n => n,87			};88		}8990		#[allow(clippy::range_plus_one)]91		fn pos(&self) -> Range<usize> {92			if self.index == self.source.len() {93				self.offset + self.index..self.offset + self.index94			} else {95				// TODO: char size96				self.offset + self.index..self.offset + self.index + 197			}98		}99	}100101	// Check that b has at least the same whitespace prefix as a and returns the102	// amount of this whitespace, otherwise returns 0.  If a has no whitespace103	// prefix than return 0.104	fn check_whitespace(a: &str, b: &str) -> usize {105		let a = a.as_bytes();106		let b = b.as_bytes();107108		for i in 0..a.len() {109			if a[i] != b' ' && a[i] != b'\t' {110				// a has run out of whitespace and b matched up to this point. Return result.111				return i;112			}113114			if i >= b.len() {115				// We ran off the edge of b while a still has whitespace. Return 0 as failure.116				return 0;117			}118119			if a[i] != b[i] {120				// a has whitespace but b does not. Return 0 as failure.121				return 0;122			}123		}124125		// We ran off the end of a and b kept up126		a.len()127	}128129	fn guess_token_end_and_bump<'a>(lex: &mut Lexer<'a, SyntaxKind>, ctx: &Context<'a>) {130		let end_index = ctx131			.rest()132			.find("|||")133			.map_or_else(|| ctx.rest().len(), |v| v + 3);134		lex.bump(ctx.index + end_index);135	}136137	debug_assert_eq!(lex.slice(), "|||");138	let mut ctx = Context {139		source: lex.remainder(),140		index: 0,141		offset: lex.span().end,142	};143144	ctx.eat_if(|v| v == '-');145146	// Skip whitespaces147	ctx.eat_while(|r| r == ' ' || r == '\t' || r == '\r');148149	// Skip \n150	match ctx.next() {151		Some('\n') => (),152		None => {153			guess_token_end_and_bump(lex, &ctx);154			return Err(UnexpectedEnd);155		}156		// Text block requires new line after |||.157		Some(_) => {158			guess_token_end_and_bump(lex, &ctx);159			return Err(MissingNewLine);160		}161	}162163	// Process leading blank lines before calculating string block indent164	while ctx.peek() == Some('\n') {165		ctx.next();166	}167168	let mut num_whitespace = check_whitespace(ctx.rest(), ctx.rest());169	let str_block_indent = &ctx.rest()[..num_whitespace];170171	if num_whitespace == 0 {172		// Text block's first line must start with whitespace173		guess_token_end_and_bump(lex, &ctx);174		return Err(MissingIndent);175	}176177	loop {178		debug_assert_ne!(num_whitespace, 0, "Unexpected value for num_whitespace");179		ctx.skip(num_whitespace);180181		loop {182			match ctx.next() {183				None => {184					guess_token_end_and_bump(lex, &ctx);185					return Err(UnexpectedEnd);186				}187				Some('\n') => break,188				Some(_) => (),189			}190		}191192		// Skip any blank lines193		while ctx.peek() == Some('\n') {194			ctx.next();195		}196197		// Look at the next line198		num_whitespace = check_whitespace(str_block_indent, ctx.rest());199		if num_whitespace == 0 {200			// End of the text block201			// let mut term_indent = String::with_capacity(num_whitespace);202			while let Some(' ' | '\t') = ctx.peek() {203				// term_indent.push(204				ctx.next().unwrap();205				// );206			}207208			if !ctx.rest().starts_with("|||") {209				// Text block not terminated with |||210				let pos = ctx.pos();211				if pos.is_empty() {212					// eof213					lex.bump(ctx.index);214					return Err(UnexpectedEnd);215				}216217				guess_token_end_and_bump(lex, &ctx);218				return Err(MissingTermination);219			}220221			// Skip '|||'222			ctx.skip(3);223			break;224		}225	}226227	lex.bump(ctx.index);228	Ok(())229}