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/* * Copyright 2019 The Starlark in Rust Authors. * Copyright (c) Facebook, Inc. and its affiliates. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * https://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ //! A data structure for tracking source positions in language implementations //! The `CodeMap` tracks all source files and maps positions within them to linear indexes as if all //! source files were concatenated. This allows a source position to be represented by a small //! 32-bit `Pos` indexing into the `CodeMap`, under the assumption that the total amount of parsed //! source code will not exceed 4GiB. The `CodeMap` can look up the source file, line, and column //! of a `Pos` or `Span`, as well as provide source code snippets for error reporting. //! //! # Example //! ``` //! use starlark::codemap::CodeMap; //! let mut codemap = CodeMap::new("test.rs".to_owned(), "fn test(){\n println!(\"Hello\");\n}\n".to_owned()); //! let file = codemap.get_file(); //! let string_literal_span = file.span.subspan(24, 31); //! //! let location = codemap.look_up_span(string_literal_span); //! assert_eq!(location.file.name(), "test.rs"); //! assert_eq!(location.begin.line, 1); //! assert_eq!(location.begin.column, 13); //! assert_eq!(location.end.line, 1); //! assert_eq!(location.end.column, 20); //! ``` use gazebo::prelude::*; use std::{ cmp, fmt, hash::{Hash, Hasher}, ops::{Add, Deref, Sub}, sync::Arc, }; /// A small, `Copy`, value representing a position in a `CodeMap`'s file. #[derive(Copy, Clone, Dupe, Hash, Eq, PartialEq, Ord, PartialOrd, Debug)] pub struct Pos(u32); impl Add<u64> for Pos { type Output = Pos; fn add(self, other: u64) -> Pos { Pos(self.0 + other as u32) } } impl Sub<Pos> for Pos { type Output = u64; fn sub(self, other: Pos) -> u64 { (self.0 - other.0) as u64 } } /// A range of text within a CodeMap. #[derive(Copy, Clone, Hash, Eq, PartialEq, Debug)] pub struct Span { /// The position in the codemap representing the first byte of the span. low: Pos, /// The position after the last byte of the span. high: Pos, } impl Span { /// Makes a span from offsets relative to the start of this span. /// /// # Panics /// * If `end < begin` /// * If `end` is beyond the length of the span pub fn subspan(self, begin: u64, end: u64) -> Span { assert!(end >= begin); assert!(self.low + end <= self.high); Span { low: self.low + begin, high: self.low + end, } } /// Checks if a span is contained within this span. pub fn contains(self, other: Span) -> bool { self.low <= other.low && self.high >= other.high } /// The position in the codemap representing the first byte of the span. pub fn low(self) -> Pos { self.low } /// The position after the last byte of the span. pub fn high(self) -> Pos { self.high } /// The length in bytes of the text of the span pub fn len(self) -> u64 { self.high - self.low } /// Create a span that encloses both `self` and `other`. pub fn merge(self, other: Span) -> Span { Span { low: cmp::min(self.low, other.low), high: cmp::max(self.high, other.high), } } } /// Associate a Span with a value of arbitrary type (e.g. an AST node). #[derive(Clone, PartialEq, Eq, Hash, Debug, Copy)] pub struct Spanned<T> { pub node: T, pub span: Span, } impl<T> Deref for Spanned<T> { type Target = T; fn deref(&self) -> &T { &self.node } } /// A data structure recording a source code file for position lookup. #[derive(Debug)] pub struct CodeMap { file: Arc<File>, } impl CodeMap { /// Creates an new `CodeMap`. pub fn new(filename: String, contents: String) -> CodeMap { let low = Pos(1); let high = low + contents.len() as u64; let mut lines = vec![low]; lines.extend( contents .match_indices('\n') .map(|(p, _)| low + (p + 1) as u64), ); CodeMap { file: Arc::new(File { span: Span { low, high }, name: filename, source: contents, lines, }), } } /// Looks up a `File` pub fn get_file(&self) -> &Arc<File> { &self.file } /// Gets the file, line, and column represented by a `Pos`. pub fn look_up_pos(&self, pos: Pos) -> Loc { let file = self.get_file(); let position = file.find_line_col(pos); Loc { file: file.dupe(), position, } } /// Gets the file and its line and column ranges represented by a `Span`. pub fn look_up_span(&self, span: Span) -> SpanLoc { let file = self.get_file(); let begin = file.find_line_col(span.low); let end = file.find_line_col(span.high); SpanLoc { file: file.dupe(), begin, end, } } } /// A `CodeMap`'s record of a source file. pub struct File { /// The span representing the entire file. pub span: Span, /// The filename as it would be displayed in an error message. name: String, /// Contents of the file. source: String, /// Byte positions of line beginnings. lines: Vec<Pos>, } impl File { /// Gets the name of the file pub fn name(&self) -> &str { &self.name } /// Gets the line number of a Pos. /// /// The lines are 0-indexed (first line is numbered 0) /// /// # Panics /// /// * If `pos` is not within this file's span pub fn find_line(&self, pos: Pos) -> usize { assert!(pos >= self.span.low); assert!(pos <= self.span.high); match self.lines.binary_search(&pos) { Ok(i) => i, Err(i) => i - 1, } } /// Gets the line and column of a Pos. /// /// # Panics /// /// * If `pos` is not with this file's span /// * If `pos` points to a byte in the middle of a UTF-8 character pub fn find_line_col(&self, pos: Pos) -> LineCol { let line = self.find_line(pos); let line_span = self.line_span(line); let byte_col = pos - line_span.low; let column = self.source_slice(line_span)[..byte_col as usize] .chars() .count(); LineCol { line, column } } /// Gets the full source text of the file pub fn source(&self) -> &str { &self.source } /// Gets the source text of a Span. /// /// # Panics /// /// * If `span` is not entirely within this file. pub fn source_slice(&self, span: Span) -> &str { assert!(self.span.contains(span)); &self.source[((span.low - self.span.low) as usize)..((span.high - self.span.low) as usize)] } /// Gets the span representing a line by line number. /// /// The line number is 0-indexed (first line is numbered 0). The returned span includes the /// line terminator. /// /// # Panics /// /// * If the line number is out of range pub fn line_span(&self, line: usize) -> Span { assert!(line < self.lines.len()); Span { low: self.lines[line], high: *self.lines.get(line + 1).unwrap_or(&self.span.high), } } /// Gets the source text of a line. /// /// The string returned does not include the terminating \r or \n characters. /// /// # Panics /// /// * If the line number is out of range pub fn source_line(&self, line: usize) -> &str { self.source_slice(self.line_span(line)) .trim_end_matches(&['\n', '\r'][..]) } /// Gets the number of lines in the file pub fn num_lines(&self) -> usize { self.lines.len() } } impl fmt::Debug for File { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { write!(f, "File({:?})", self.name) } } impl PartialEq for File { /// Compares by identity fn eq(&self, other: &File) -> bool { std::ptr::eq(self, other) } } impl Eq for File {} impl Hash for File { fn hash<H: Hasher>(&self, hasher: &mut H) { self.span.hash(hasher); } } /// A line and column. #[derive(Copy, Clone, Hash, Eq, PartialEq, Debug)] pub struct LineCol { /// The line number within the file (0-indexed). pub line: usize, /// The column within the line (0-indexed). pub column: usize, } /// A file, and a line and column within it. #[derive(Clone, Eq, PartialEq, Debug)] pub struct Loc { pub file: Arc<File>, pub position: LineCol, } impl fmt::Display for Loc { /// Formats the location as `filename:line:column`, with a 1-indexed /// line and column. fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { write!( f, "{}:{}:{}", self.file.name, self.position.line + 1, self.position.column + 1 ) } } /// A file, and a line and column range within it. #[derive(Clone, Eq, PartialEq, Debug)] pub struct SpanLoc { pub file: Arc<File>, pub begin: LineCol, pub end: LineCol, } impl fmt::Display for SpanLoc { /// Formats the span as `filename:start_line:start_column: end_line:end_column`, /// or if the span is zero-length, `filename:line:column`, with a 1-indexed line and column. fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { if self.begin == self.end { write!( f, "{}:{}:{}", self.file.name, self.begin.line + 1, self.begin.column + 1 ) } else { write!( f, "{}:{}:{}: {}:{}", self.file.name, self.begin.line + 1, self.begin.column + 1, self.end.line + 1, self.end.column + 1 ) } } } #[test] fn test_codemap() { let codemap = CodeMap::new("test1.rs".to_owned(), "abcd\nefghij\nqwerty".to_owned()); assert_eq!(codemap.get_file().name(), "test1.rs"); assert_eq!(codemap.get_file().name(), "test1.rs"); let f = codemap.get_file(); assert_eq!(f.name, "test1.rs"); assert_eq!( f.find_line_col(f.span.low()), LineCol { line: 0, column: 0 } ); assert_eq!( f.find_line_col(f.span.low() + 4), LineCol { line: 0, column: 4 } ); assert_eq!( f.find_line_col(f.span.low() + 5), LineCol { line: 1, column: 0 } ); assert_eq!( f.find_line_col(f.span.low() + 16), LineCol { line: 2, column: 4 } ); } #[test] fn test_issue2() { let content = "a \nxyz\r\n"; let codemap = CodeMap::new("<test>".to_owned(), content.to_owned()); let file = codemap.get_file(); let span = file.span.subspan(2, 3); assert_eq!( codemap.look_up_span(span), SpanLoc { file: file.dupe(), begin: LineCol { line: 0, column: 2 }, end: LineCol { line: 1, column: 0 } } ); assert_eq!(file.source_line(0), "a "); assert_eq!(file.source_line(1), "xyz"); assert_eq!(file.source_line(2), ""); } #[test] fn test_multibyte() { let content = "65°00′N 18°00′W 汉语\n🔬"; let codemap = CodeMap::new("<test>".to_owned(), content.to_owned()); let file = codemap.get_file(); assert_eq!( codemap.look_up_pos(file.span.low() + 21), Loc { file: file.dupe(), position: LineCol { line: 0, column: 15 } } ); assert_eq!( codemap.look_up_pos(file.span.low() + 28), Loc { file: file.dupe(), position: LineCol { line: 0, column: 18 } } ); assert_eq!( codemap.look_up_pos(file.span.low() + 33), Loc { file: file.dupe(), position: LineCol { line: 1, column: 1 } } ); }