Moved FileMap construction to it's own constructor.

The rationale is that BOM stripping is needed for lazy source loading
for external crates, and duplication can be avoided by moving the
corresponding functionality to libsyntax_pos.

2 files changed, 38 insertions, 0 deletions

diff --git a/src/libsyntax_pos/Cargo.toml b/src/libsyntax_pos/Cargo.toml
index 760aaa8a957..dd8129bab51 100644
--- a/src/libsyntax_pos/Cargo.toml
+++ b/src/libsyntax_pos/Cargo.toml
@@ -10,3 +10,4 @@ crate-type = ["dylib"]
 
 [dependencies]
 serialize = { path = "../libserialize" }
+rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/libsyntax_pos/lib.rs b/src/libsyntax_pos/lib.rs
index caea1497181..75ce8b675f3 100644
--- a/src/libsyntax_pos/lib.rs
+++ b/src/libsyntax_pos/lib.rs
@@ -38,6 +38,11 @@ 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};
 
@@ -522,6 +527,31 @@ impl fmt::Debug for FileMap {
 }
 
 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
@@ -621,6 +651,13 @@ impl FileMap {
     }
 }
 
+/// Remove utf-8 BOM if any.
+fn remove_bom(src: &mut String) {
+    if src.starts_with("\u{feff}") {
+        src.drain(..3);
+    }
+}
+
 // _____________________________________________________________________________
 // Pos, BytePos, CharPos
 //