Merge pull request dtolnay#442 from dtolnay/byterange

Expose Span::byte_range

Author: dtolnay

build/probe.rs

@@ -6,9 +6,13 @@
 
 extern crate proc_macro;
 
-use core::ops::RangeBounds;
+use core::ops::{Range, RangeBounds};
 use proc_macro::{Literal, Span};
 
+pub fn byte_range(this: &Span) -> Range<usize> {
+    this.byte_range()
+}
+
 pub fn join(this: &Span, other: Span) -> Option<Span> {
     this.join(other)
 }

src/fallback.rs

@@ -11,6 +11,8 @@ use core::cell::RefCell;
 use core::cmp;
 use core::fmt::{self, Debug, Display, Write};
 use core::mem::ManuallyDrop;
+#[cfg(span_locations)]
+use core::ops::Range;
 use core::ops::RangeBounds;
 use core::ptr;
 use core::str::FromStr;
@@ -372,7 +374,7 @@ impl FileInfo {
         span.lo >= self.span.lo && span.hi <= self.span.hi
     }
 
-    fn source_text(&mut self, span: Span) -> String {
+    fn byte_range(&mut self, span: Span) -> Range<usize> {
         let lo_char = (span.lo - self.span.lo) as usize;
 
         // Look up offset of the largest already-computed char index that is
@@ -401,11 +403,15 @@ impl FileInfo {
 
         let trunc_lo = &self.source_text[lo_byte..];
         let char_len = (span.hi - span.lo) as usize;
-        let source_text = match trunc_lo.char_indices().nth(char_len) {
-            Some((offset, _ch)) => &trunc_lo[..offset],
-            None => trunc_lo,
-        };
-        source_text.to_owned()
+        lo_byte..match trunc_lo.char_indices().nth(char_len) {
+            Some((offset, _ch)) => lo_byte + offset,
+            None => self.source_text.len(),
+        }
+    }
+
+    fn source_text(&mut self, span: Span) -> String {
+        let byte_range = self.byte_range(span);
+        self.source_text[byte_range].to_owned()
     }
 }
 
@@ -547,6 +553,21 @@ impl Span {
         })
     }
 
+    #[cfg(span_locations)]
+    pub fn byte_range(&self) -> Range<usize> {
+        #[cfg(fuzzing)]
+        return 0..0;
+
+        #[cfg(not(fuzzing))]
+        {
+            if self.is_call_site() {
+                0..0
+            } else {
+                SOURCE_MAP.with(|sm| sm.borrow_mut().fileinfo_mut(*self).byte_range(*self))
+            }
+        }
+    }
+
     #[cfg(span_locations)]
     pub fn start(&self) -> LineColumn {
         #[cfg(fuzzing)]

src/lib.rs

@@ -164,6 +164,8 @@ use crate::marker::{ProcMacroAutoTraits, MARKER};
 use core::cmp::Ordering;
 use core::fmt::{self, Debug, Display};
 use core::hash::{Hash, Hasher};
+#[cfg(span_locations)]
+use core::ops::Range;
 use core::ops::RangeBounds;
 use core::str::FromStr;
 use std::error::Error;
@@ -472,6 +474,21 @@ impl Span {
         SourceFile::_new(self.inner.source_file())
     }
 
+    /// Returns the span's byte position range in the source file.
+    ///
+    /// This method requires the `"span-locations"` feature to be enabled.
+    ///
+    /// When executing in a procedural macro context, the returned range is only
+    /// accurate if compiled with a nightly toolchain. The stable toolchain does
+    /// not have this information available. When executing outside of a
+    /// procedural macro, such as main.rs or build.rs, the byte range is always
+    /// accurate regardless of toolchain.
+    #[cfg(span_locations)]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "span-locations")))]
+    pub fn byte_range(&self) -> Range<usize> {
+        self.inner.byte_range()
+    }
+
     /// Get the starting line/column in the source file for this span.
     ///
     /// This method requires the `"span-locations"` feature to be enabled.

src/wrapper.rs

@@ -3,6 +3,8 @@ use crate::detection::inside_proc_macro;
 use crate::location::LineColumn;
 use crate::{fallback, Delimiter, Punct, Spacing, TokenTree};
 use core::fmt::{self, Debug, Display};
+#[cfg(span_locations)]
+use core::ops::Range;
 use core::ops::RangeBounds;
 use core::str::FromStr;
 use std::panic;
@@ -460,6 +462,17 @@ impl Span {
         }
     }
 
+    #[cfg(span_locations)]
+    pub fn byte_range(&self) -> Range<usize> {
+        match self {
+            #[cfg(proc_macro_span)]
+            Span::Compiler(s) => s.byte_range(),
+            #[cfg(not(proc_macro_span))]
+            Span::Compiler(_) => 0..0,
+            Span::Fallback(s) => s.byte_range(),
+        }
+    }
+
     #[cfg(span_locations)]
     pub fn start(&self) -> LineColumn {
         match self {