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rust/src/libsyntax_pos/lib.rs

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// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! The source positions and related helper functions
//!
//! # Note
//!
//! This API is completely unstable and subject to change.
#![crate_name = "syntax_pos"]
#![crate_type = "dylib"]
#![crate_type = "rlib"]
#![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
html_root_url = "https://doc.rust-lang.org/nightly/")]
#![deny(warnings)]
#![feature(const_fn)]
#![feature(custom_attribute)]
#![feature(i128_type)]
#![feature(optin_builtin_traits)]
#![allow(unused_attributes)]
#![feature(specialization)]
#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
#![cfg_attr(stage0, feature(rustc_private))]
#![cfg_attr(stage0, feature(staged_api))]
use std::cell::{Cell, RefCell};
use std::ops::{Add, Sub};
use std::rc::Rc;
use std::cmp;
use std::fmt;
use std::hash::Hasher;
use rustc_data_structures::stable_hasher::StableHasher;
extern crate rustc_data_structures;
use serialize::{Encodable, Decodable, Encoder, Decoder};
extern crate serialize;
extern crate serialize as rustc_serialize; // used by deriving
pub mod hygiene;
pub use hygiene::{SyntaxContext, ExpnInfo, ExpnFormat, NameAndSpan};
pub mod symbol;
pub type FileName = String;
/// Spans represent a region of code, used for error reporting. Positions in spans
/// are *absolute* positions from the beginning of the codemap, not positions
/// relative to FileMaps. Methods on the CodeMap can be used to relate spans back
/// to the original source.
/// You must be careful if the span crosses more than one file - you will not be
/// able to use many of the functions on spans in codemap and you cannot assume
/// that the length of the span = hi - lo; there may be space in the BytePos
/// range between files.
#[derive(Clone, Copy, Hash, PartialEq, Eq, Ord, PartialOrd)]
pub struct Span {
pub lo: BytePos,
pub hi: BytePos,
/// Information about where the macro came from, if this piece of
/// code was created by a macro expansion.
pub ctxt: SyntaxContext,
}
/// A collection of spans. Spans have two orthogonal attributes:
///
/// - they can be *primary spans*. In this case they are the locus of
/// the error, and would be rendered with `^^^`.
/// - they can have a *label*. In this case, the label is written next
/// to the mark in the snippet when we render.
#[derive(Clone, Debug, Hash, PartialEq, Eq, RustcEncodable, RustcDecodable)]
pub struct MultiSpan {
primary_spans: Vec<Span>,
span_labels: Vec<(Span, String)>,
}
impl Span {
/// Returns a new span representing just the end-point of this span
pub fn end_point(self) -> Span {
let lo = cmp::max(self.hi.0 - 1, self.lo.0);
Span { lo: BytePos(lo), ..self }
}
/// Returns a new span representing the next character after the end-point of this span
pub fn next_point(self) -> Span {
let lo = cmp::max(self.hi.0, self.lo.0 + 1);
Span { lo: BytePos(lo), hi: BytePos(lo), ..self }
}
/// Returns `self` if `self` is not the dummy span, and `other` otherwise.
pub fn substitute_dummy(self, other: Span) -> Span {
if self.source_equal(&DUMMY_SP) { other } else { self }
}
pub fn contains(self, other: Span) -> bool {
self.lo <= other.lo && other.hi <= self.hi
}
/// Return true if the spans are equal with regards to the source text.
///
/// Use this instead of `==` when either span could be generated code,
/// and you only care that they point to the same bytes of source text.
pub fn source_equal(&self, other: &Span) -> bool {
self.lo == other.lo && self.hi == other.hi
}
/// Returns `Some(span)`, where the start is trimmed by the end of `other`
pub fn trim_start(self, other: Span) -> Option<Span> {
if self.hi > other.hi {
Some(Span { lo: cmp::max(self.lo, other.hi), .. self })
} else {
None
}
}
/// Return the source span - this is either the supplied span, or the span for
/// the macro callsite that expanded to it.
pub fn source_callsite(self) -> Span {
self.ctxt.outer().expn_info().map(|info| info.call_site.source_callsite()).unwrap_or(self)
}
/// Return the source callee.
///
/// Returns None if the supplied span has no expansion trace,
/// else returns the NameAndSpan for the macro definition
/// corresponding to the source callsite.
pub fn source_callee(self) -> Option<NameAndSpan> {
fn source_callee(info: ExpnInfo) -> NameAndSpan {
match info.call_site.ctxt.outer().expn_info() {
Some(info) => source_callee(info),
None => info.callee,
}
}
self.ctxt.outer().expn_info().map(source_callee)
}
/// Check if a span is "internal" to a macro in which #[unstable]
/// items can be used (that is, a macro marked with
/// `#[allow_internal_unstable]`).
pub fn allows_unstable(&self) -> bool {
match self.ctxt.outer().expn_info() {
Some(info) => info.callee.allow_internal_unstable,
None => false,
}
}
pub fn macro_backtrace(mut self) -> Vec<MacroBacktrace> {
let mut prev_span = DUMMY_SP;
let mut result = vec![];
loop {
let info = match self.ctxt.outer().expn_info() {
Some(info) => info,
None => break,
};
let (pre, post) = match info.callee.format {
ExpnFormat::MacroAttribute(..) => ("#[", "]"),
ExpnFormat::MacroBang(..) => ("", "!"),
ExpnFormat::CompilerDesugaring(..) => ("desugaring of `", "`"),
};
let macro_decl_name = format!("{}{}{}", pre, info.callee.name(), post);
let def_site_span = info.callee.span;
// Don't print recursive invocations
if !info.call_site.source_equal(&prev_span) {
result.push(MacroBacktrace {
call_site: info.call_site,
macro_decl_name: macro_decl_name,
def_site_span: def_site_span,
});
}
prev_span = self;
self = info.call_site;
}
result
}
pub fn to(self, end: Span) -> Span {
// FIXME(jseyfried): self.ctxt should always equal end.ctxt here (c.f. issue #23480)
if end.ctxt == SyntaxContext::empty() {
Span { lo: self.lo, ..end }
} else {
Span { hi: end.hi, ..self }
}
}
pub fn between(self, end: Span) -> Span {
Span {
lo: self.hi,
hi: end.lo,
ctxt: if end.ctxt == SyntaxContext::empty() {
end.ctxt
} else {
self.ctxt
}
}
}
pub fn until(self, end: Span) -> Span {
Span {
lo: self.lo,
hi: end.lo,
ctxt: if end.ctxt == SyntaxContext::empty() {
end.ctxt
} else {
self.ctxt
}
}
}
}
#[derive(Clone, Debug)]
pub struct SpanLabel {
/// The span we are going to include in the final snippet.
pub span: Span,
/// Is this a primary span? This is the "locus" of the message,
/// and is indicated with a `^^^^` underline, versus `----`.
pub is_primary: bool,
/// What label should we attach to this span (if any)?
pub label: Option<String>,
}
impl serialize::UseSpecializedEncodable for Span {
fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
s.emit_struct("Span", 2, |s| {
s.emit_struct_field("lo", 0, |s| {
self.lo.encode(s)
})?;
s.emit_struct_field("hi", 1, |s| {
self.hi.encode(s)
})
})
}
}
impl serialize::UseSpecializedDecodable for Span {
fn default_decode<D: Decoder>(d: &mut D) -> Result<Span, D::Error> {
d.read_struct("Span", 2, |d| {
let lo = d.read_struct_field("lo", 0, Decodable::decode)?;
let hi = d.read_struct_field("hi", 1, Decodable::decode)?;
Ok(Span { lo: lo, hi: hi, ctxt: NO_EXPANSION })
})
}
}
fn default_span_debug(span: Span, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "Span {{ lo: {:?}, hi: {:?}, ctxt: {:?} }}",
span.lo, span.hi, span.ctxt)
}
impl fmt::Debug for Span {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
SPAN_DEBUG.with(|span_debug| span_debug.get()(*self, f))
}
}
pub const DUMMY_SP: Span = Span { lo: BytePos(0), hi: BytePos(0), ctxt: NO_EXPANSION };
impl MultiSpan {
pub fn new() -> MultiSpan {
MultiSpan {
primary_spans: vec![],
span_labels: vec![]
}
}
pub fn from_span(primary_span: Span) -> MultiSpan {
MultiSpan {
primary_spans: vec![primary_span],
span_labels: vec![]
}
}
pub fn from_spans(vec: Vec<Span>) -> MultiSpan {
MultiSpan {
primary_spans: vec,
span_labels: vec![]
}
}
pub fn push_span_label(&mut self, span: Span, label: String) {
self.span_labels.push((span, label));
}
/// Selects the first primary span (if any)
pub fn primary_span(&self) -> Option<Span> {
self.primary_spans.first().cloned()
}
/// Returns all primary spans.
pub fn primary_spans(&self) -> &[Span] {
&self.primary_spans
}
/// Replaces all occurances of one Span with another. Used to move Spans in areas that don't
/// display well (like std macros). Returns true if replacements occurred.
pub fn replace(&mut self, before: Span, after: Span) -> bool {
let mut replacements_occurred = false;
for primary_span in &mut self.primary_spans {
if *primary_span == before {
*primary_span = after;
replacements_occurred = true;
}
}
for span_label in &mut self.span_labels {
if span_label.0 == before {
span_label.0 = after;
replacements_occurred = true;
}
}
replacements_occurred
}
/// Returns the strings to highlight. We always ensure that there
/// is an entry for each of the primary spans -- for each primary
/// span P, if there is at least one label with span P, we return
/// those labels (marked as primary). But otherwise we return
/// `SpanLabel` instances with empty labels.
pub fn span_labels(&self) -> Vec<SpanLabel> {
let is_primary = |span| self.primary_spans.contains(&span);
let mut span_labels = vec![];
for &(span, ref label) in &self.span_labels {
span_labels.push(SpanLabel {
span: span,
is_primary: is_primary(span),
label: Some(label.clone())
});
}
for &span in &self.primary_spans {
if !span_labels.iter().any(|sl| sl.span == span) {
span_labels.push(SpanLabel {
span: span,
is_primary: true,
label: None
});
}
}
span_labels
}
}
impl From<Span> for MultiSpan {
fn from(span: Span) -> MultiSpan {
MultiSpan::from_span(span)
}
}
pub const NO_EXPANSION: SyntaxContext = SyntaxContext::empty();
/// Identifies an offset of a multi-byte character in a FileMap
#[derive(Copy, Clone, RustcEncodable, RustcDecodable, Eq, PartialEq)]
pub struct MultiByteChar {
/// The absolute offset of the character in the CodeMap
pub pos: BytePos,
/// The number of bytes, >=2
pub bytes: usize,
}
/// A single source in the CodeMap.
#[derive(Clone)]
pub struct FileMap {
/// The name of the file that the source came from, source that doesn't
/// originate from files has names between angle brackets by convention,
/// e.g. `<anon>`
pub name: FileName,
/// True if the `name` field above has been modified by -Zremap-path-prefix
pub name_was_remapped: bool,
/// Indicates which crate this FileMap was imported from.
pub crate_of_origin: u32,
/// The complete source code
pub src: Option<Rc<String>>,
/// The source code's hash
pub src_hash: u128,
/// The start position of this source in the CodeMap
pub start_pos: BytePos,
/// The end position of this source in the CodeMap
pub end_pos: BytePos,
/// Locations of lines beginnings in the source code
pub lines: RefCell<Vec<BytePos>>,
/// Locations of multi-byte characters in the source code
pub multibyte_chars: RefCell<Vec<MultiByteChar>>,
}
impl Encodable for FileMap {
fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
s.emit_struct("FileMap", 7, |s| {
s.emit_struct_field("name", 0, |s| self.name.encode(s))?;
s.emit_struct_field("name_was_remapped", 1, |s| self.name_was_remapped.encode(s))?;
s.emit_struct_field("src_hash", 6, |s| self.src_hash.encode(s))?;
s.emit_struct_field("start_pos", 2, |s| self.start_pos.encode(s))?;
s.emit_struct_field("end_pos", 3, |s| self.end_pos.encode(s))?;
s.emit_struct_field("lines", 4, |s| {
let lines = self.lines.borrow();
// store the length
s.emit_u32(lines.len() as u32)?;
if !lines.is_empty() {
// In order to preserve some space, we exploit the fact that
// the lines list is sorted and individual lines are
// probably not that long. Because of that we can store lines
// as a difference list, using as little space as possible
// for the differences.
let max_line_length = if lines.len() == 1 {
0
} else {
lines.windows(2)
.map(|w| w[1] - w[0])
.map(|bp| bp.to_usize())
.max()
.unwrap()
};
let bytes_per_diff: u8 = match max_line_length {
0 ... 0xFF => 1,
0x100 ... 0xFFFF => 2,
_ => 4
};
// Encode the number of bytes used per diff.
bytes_per_diff.encode(s)?;
// Encode the first element.
lines[0].encode(s)?;
let diff_iter = (&lines[..]).windows(2)
.map(|w| (w[1] - w[0]));
match bytes_per_diff {
1 => for diff in diff_iter { (diff.0 as u8).encode(s)? },
2 => for diff in diff_iter { (diff.0 as u16).encode(s)? },
4 => for diff in diff_iter { diff.0.encode(s)? },
_ => unreachable!()
}
}
Ok(())
})?;
s.emit_struct_field("multibyte_chars", 5, |s| {
(*self.multibyte_chars.borrow()).encode(s)
})
})
}
}
impl Decodable for FileMap {
fn decode<D: Decoder>(d: &mut D) -> Result<FileMap, D::Error> {
d.read_struct("FileMap", 6, |d| {
let name: String = d.read_struct_field("name", 0, |d| Decodable::decode(d))?;
let name_was_remapped: bool =
d.read_struct_field("name_was_remapped", 1, |d| Decodable::decode(d))?;
let src_hash: u128 =
d.read_struct_field("src_hash", 6, |d| Decodable::decode(d))?;
let start_pos: BytePos =
d.read_struct_field("start_pos", 2, |d| Decodable::decode(d))?;
let end_pos: BytePos = d.read_struct_field("end_pos", 3, |d| Decodable::decode(d))?;
let lines: Vec<BytePos> = d.read_struct_field("lines", 4, |d| {
let num_lines: u32 = Decodable::decode(d)?;
let mut lines = Vec::with_capacity(num_lines as usize);
if num_lines > 0 {
// Read the number of bytes used per diff.
let bytes_per_diff: u8 = Decodable::decode(d)?;
// Read the first element.
let mut line_start: BytePos = Decodable::decode(d)?;
lines.push(line_start);
for _ in 1..num_lines {
let diff = match bytes_per_diff {
1 => d.read_u8()? as u32,
2 => d.read_u16()? as u32,
4 => d.read_u32()?,
_ => unreachable!()
};
line_start = line_start + BytePos(diff);
lines.push(line_start);
}
}
Ok(lines)
})?;
let multibyte_chars: Vec<MultiByteChar> =
d.read_struct_field("multibyte_chars", 5, |d| Decodable::decode(d))?;
Ok(FileMap {
name: name,
name_was_remapped: name_was_remapped,
// `crate_of_origin` has to be set by the importer.
// This value matches up with rustc::hir::def_id::INVALID_CRATE.
// That constant is not available here unfortunately :(
crate_of_origin: ::std::u32::MAX - 1,
start_pos: start_pos,
end_pos: end_pos,
src: None,
src_hash: src_hash,
lines: RefCell::new(lines),
multibyte_chars: RefCell::new(multibyte_chars)
})
})
}
}
impl fmt::Debug for FileMap {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
write!(fmt, "FileMap({})", self.name)
}
}
impl FileMap {
pub fn new(name: FileName,
name_was_remapped: bool,
mut src: String,
start_pos: BytePos) -> FileMap {
remove_bom(&mut src);
let mut hasher: StableHasher<u128> = StableHasher::new();
hasher.write(src.as_bytes());
let src_hash = hasher.finish();
let end_pos = start_pos.to_usize() + src.len();
FileMap {
name: name,
name_was_remapped: name_was_remapped,
crate_of_origin: 0,
src: Some(Rc::new(src)),
src_hash: src_hash,
start_pos: start_pos,
end_pos: Pos::from_usize(end_pos),
lines: RefCell::new(Vec::new()),
multibyte_chars: RefCell::new(Vec::new()),
}
}
/// EFFECT: register a start-of-line offset in the
/// table of line-beginnings.
/// UNCHECKED INVARIANT: these offsets must be added in the right
/// order and must be in the right places; there is shared knowledge
/// about what ends a line between this file and parse.rs
/// WARNING: pos param here is the offset relative to start of CodeMap,
/// and CodeMap will append a newline when adding a filemap without a newline at the end,
/// so the safe way to call this is with value calculated as
/// filemap.start_pos + newline_offset_relative_to_the_start_of_filemap.
pub fn next_line(&self, pos: BytePos) {
// the new charpos must be > the last one (or it's the first one).
let mut lines = self.lines.borrow_mut();
let line_len = lines.len();
assert!(line_len == 0 || ((*lines)[line_len - 1] < pos));
lines.push(pos);
}
/// get a line from the list of pre-computed line-beginnings.
/// line-number here is 0-based.
pub fn get_line(&self, line_number: usize) -> Option<&str> {
match self.src {
Some(ref src) => {
let lines = self.lines.borrow();
lines.get(line_number).map(|&line| {
let begin: BytePos = line - self.start_pos;
let begin = begin.to_usize();
// We can't use `lines.get(line_number+1)` because we might
// be parsing when we call this function and thus the current
// line is the last one we have line info for.
let slice = &src[begin..];
match slice.find('\n') {
Some(e) => &slice[..e],
None => slice
}
})
}
None => None
}
}
pub fn record_multibyte_char(&self, pos: BytePos, bytes: usize) {
assert!(bytes >=2 && bytes <= 4);
let mbc = MultiByteChar {
pos: pos,
bytes: bytes,
};
self.multibyte_chars.borrow_mut().push(mbc);
}
pub fn is_real_file(&self) -> bool {
!(self.name.starts_with("<") &&
self.name.ends_with(">"))
}
pub fn is_imported(&self) -> bool {
self.src.is_none()
}
pub fn byte_length(&self) -> u32 {
self.end_pos.0 - self.start_pos.0
}
pub fn count_lines(&self) -> usize {
self.lines.borrow().len()
}
/// Find the line containing the given position. The return value is the
/// index into the `lines` array of this FileMap, not the 1-based line
/// number. If the filemap is empty or the position is located before the
/// first line, None is returned.
pub fn lookup_line(&self, pos: BytePos) -> Option<usize> {
let lines = self.lines.borrow();
if lines.len() == 0 {
return None;
}
let line_index = lookup_line(&lines[..], pos);
assert!(line_index < lines.len() as isize);
if line_index >= 0 {
Some(line_index as usize)
} else {
None
}
}
pub fn line_bounds(&self, line_index: usize) -> (BytePos, BytePos) {
if self.start_pos == self.end_pos {
return (self.start_pos, self.end_pos);
}
let lines = self.lines.borrow();
assert!(line_index < lines.len());
if line_index == (lines.len() - 1) {
(lines[line_index], self.end_pos)
} else {
(lines[line_index], lines[line_index + 1])
}
}
}
/// Remove utf-8 BOM if any.
fn remove_bom(src: &mut String) {
if src.starts_with("\u{feff}") {
src.drain(..3);
}
}
// _____________________________________________________________________________
// Pos, BytePos, CharPos
//
pub trait Pos {
fn from_usize(n: usize) -> Self;
fn to_usize(&self) -> usize;
}
/// A byte offset. Keep this small (currently 32-bits), as AST contains
/// a lot of them.
#[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
pub struct BytePos(pub u32);
/// A character offset. Because of multibyte utf8 characters, a byte offset
/// is not equivalent to a character offset. The CodeMap will convert BytePos
/// values to CharPos values as necessary.
#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
pub struct CharPos(pub usize);
// FIXME: Lots of boilerplate in these impls, but so far my attempts to fix
// have been unsuccessful
impl Pos for BytePos {
fn from_usize(n: usize) -> BytePos { BytePos(n as u32) }
fn to_usize(&self) -> usize { let BytePos(n) = *self; n as usize }
}
impl Add for BytePos {
type Output = BytePos;
fn add(self, rhs: BytePos) -> BytePos {
BytePos((self.to_usize() + rhs.to_usize()) as u32)
}
}
impl Sub for BytePos {
type Output = BytePos;
fn sub(self, rhs: BytePos) -> BytePos {
BytePos((self.to_usize() - rhs.to_usize()) as u32)
}
}
impl Encodable for BytePos {
fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
s.emit_u32(self.0)
}
}
impl Decodable for BytePos {
fn decode<D: Decoder>(d: &mut D) -> Result<BytePos, D::Error> {
Ok(BytePos(d.read_u32()?))
}
}
impl Pos for CharPos {
fn from_usize(n: usize) -> CharPos { CharPos(n) }
fn to_usize(&self) -> usize { let CharPos(n) = *self; n }
}
impl Add for CharPos {
type Output = CharPos;
fn add(self, rhs: CharPos) -> CharPos {
CharPos(self.to_usize() + rhs.to_usize())
}
}
impl Sub for CharPos {
type Output = CharPos;
fn sub(self, rhs: CharPos) -> CharPos {
CharPos(self.to_usize() - rhs.to_usize())
}
}
// _____________________________________________________________________________
// Loc, LocWithOpt, FileMapAndLine, FileMapAndBytePos
//
/// A source code location used for error reporting
#[derive(Debug, Clone)]
pub struct Loc {
/// Information about the original source
pub file: Rc<FileMap>,
/// The (1-based) line number
pub line: usize,
/// The (0-based) column offset
pub col: CharPos
}
/// A source code location used as the result of lookup_char_pos_adj
// Actually, *none* of the clients use the filename *or* file field;
// perhaps they should just be removed.
#[derive(Debug)]
pub struct LocWithOpt {
pub filename: FileName,
pub line: usize,
pub col: CharPos,
pub file: Option<Rc<FileMap>>,
}
// used to be structural records. Better names, anyone?
#[derive(Debug)]
pub struct FileMapAndLine { pub fm: Rc<FileMap>, pub line: usize }
#[derive(Debug)]
pub struct FileMapAndBytePos { pub fm: Rc<FileMap>, pub pos: BytePos }
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub struct LineInfo {
/// Index of line, starting from 0.
pub line_index: usize,
/// Column in line where span begins, starting from 0.
pub start_col: CharPos,
/// Column in line where span ends, starting from 0, exclusive.
pub end_col: CharPos,
}
pub struct FileLines {
pub file: Rc<FileMap>,
pub lines: Vec<LineInfo>
}
thread_local!(pub static SPAN_DEBUG: Cell<fn(Span, &mut fmt::Formatter) -> fmt::Result> =
Cell::new(default_span_debug));
pub struct MacroBacktrace {
/// span where macro was applied to generate this code
pub call_site: Span,
/// name of macro that was applied (e.g., "foo!" or "#[derive(Eq)]")
pub macro_decl_name: String,
/// span where macro was defined (if known)
pub def_site_span: Option<Span>,
}
// _____________________________________________________________________________
// SpanLinesError, SpanSnippetError, DistinctSources, MalformedCodemapPositions
//
pub type FileLinesResult = Result<FileLines, SpanLinesError>;
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum SpanLinesError {
IllFormedSpan(Span),
DistinctSources(DistinctSources),
}
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum SpanSnippetError {
IllFormedSpan(Span),
DistinctSources(DistinctSources),
MalformedForCodemap(MalformedCodemapPositions),
SourceNotAvailable { filename: String }
}
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct DistinctSources {
pub begin: (String, BytePos),
pub end: (String, BytePos)
}
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct MalformedCodemapPositions {
pub name: String,
pub source_len: usize,
pub begin_pos: BytePos,
pub end_pos: BytePos
}
// Given a slice of line start positions and a position, returns the index of
// the line the position is on. Returns -1 if the position is located before
// the first line.
fn lookup_line(lines: &[BytePos], pos: BytePos) -> isize {
match lines.binary_search(&pos) {
Ok(line) => line as isize,
Err(line) => line as isize - 1
}
}
#[cfg(test)]
mod tests {
use super::{lookup_line, BytePos};
#[test]
fn test_lookup_line() {
let lines = &[BytePos(3), BytePos(17), BytePos(28)];
assert_eq!(lookup_line(lines, BytePos(0)), -1);
assert_eq!(lookup_line(lines, BytePos(3)), 0);
assert_eq!(lookup_line(lines, BytePos(4)), 0);
assert_eq!(lookup_line(lines, BytePos(16)), 0);
assert_eq!(lookup_line(lines, BytePos(17)), 1);
assert_eq!(lookup_line(lines, BytePos(18)), 1);
assert_eq!(lookup_line(lines, BytePos(28)), 2);
assert_eq!(lookup_line(lines, BytePos(29)), 2);
}
}
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