Merge pull request #294 from sinhpham/diff_write_mode

Add diff write mode https://github.com/nrc/rustfmt/issues/261

7 files changed, 137 insertions, 106 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 63854ccae46..30f07fd4f98 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2,7 +2,7 @@
 name = "rustfmt"
 version = "0.0.1"
 dependencies = [
- "diff 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "diff 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 0.1.41 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-serialize 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
  "strings 0.0.1 (git+https://github.com/nrc/strings.rs.git)",
@@ -21,7 +21,7 @@ dependencies = [
 
 [[package]]
 name = "diff"
-version = "0.1.4"
+version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
diff --git a/Cargo.toml b/Cargo.toml
index 597eb8f942d..9cb4f929344 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,7 +17,7 @@ toml = "0.1.20"
 rustc-serialize = "0.3.14"
 unicode-segmentation = "0.1.2"
 regex = "0.1.41"
+diff = "0.1.5"
+term = "0.2.11"
 
 [dev-dependencies]
-diff = "0.1.0"
-term = "0.2"
diff --git a/src/bin/rustfmt.rs b/src/bin/rustfmt.rs
index 86a4faa05f5..9f2387f5c2c 100644
--- a/src/bin/rustfmt.rs
+++ b/src/bin/rustfmt.rs
@@ -82,7 +82,7 @@ fn main() {
 }
 
 fn print_usage<S: Into<String>>(reason: S) {
-    println!("{}\n\r usage: rustfmt [-h Help] [--write-mode=[replace|overwrite|display]] <file_name>", reason.into());
+    println!("{}\n\r usage: rustfmt [-h Help] [--write-mode=[replace|overwrite|display|diff]] <file_name>", reason.into());
 }
 
 fn determine_params<I>(args: I) -> Option<(Vec<String>, WriteMode)>
diff --git a/src/filemap.rs b/src/filemap.rs
index 8bb5a7285bb..91aaece6558 100644
--- a/src/filemap.rs
+++ b/src/filemap.rs
@@ -14,10 +14,11 @@
 use strings::string_buffer::StringBuffer;
 use std::collections::HashMap;
 use std::fs::{self, File};
-use std::io::{self, Write, stdout};
+use std::io::{self, Write, Read, stdout};
 use WriteMode;
 use NewlineStyle;
 use config::Config;
+use rustfmt_diff::{make_diff, print_diff};
 
 // A map of the files of a crate, with their new content
 pub type FileMap = HashMap<String, StringBuffer>;
@@ -104,6 +105,17 @@ fn write_file(text: &StringBuffer,
             let stdout_lock = stdout.lock();
             try!(write_system_newlines(stdout_lock, text, config));
         }
+        WriteMode::Diff => {
+            println!("Diff of {}:\n", filename);
+            let mut f = try!(File::open(filename));
+            let mut ori_text = String::new();
+            try!(f.read_to_string(&mut ori_text));
+            let mut v = Vec::new();
+            try!(write_system_newlines(&mut v, text, config));
+            let fmt_text = String::from_utf8(v).unwrap();
+            let diff = make_diff(&ori_text, &fmt_text, 3);
+            print_diff(diff, |line_num| format!("\nDiff at line {}:", line_num));
+        }
         WriteMode::Return(_) => {
             // io::Write is not implemented for String, working around with
             // Vec<u8>
diff --git a/src/lib.rs b/src/lib.rs
index ab748f62a95..7975c77e06d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -30,6 +30,8 @@ extern crate strings;
 
 extern crate unicode_segmentation;
 extern crate regex;
+extern crate diff;
+extern crate term;
 
 use rustc::session::Session;
 use rustc::session::config as rustc_config;
@@ -67,6 +69,7 @@ mod rewrite;
 mod string;
 mod comment;
 mod modules;
+pub mod rustfmt_diff;
 
 const MIN_STRING: usize = 10;
 // When we get scoped annotations, we should have rustfmt::skip.
@@ -82,6 +85,8 @@ pub enum WriteMode {
     NewFile(&'static str),
     // Write the output to stdout.
     Display,
+    // Write the diff to stdout.
+    Diff,
     // Return the result as a mapping from filenames to Strings.
     Return(&'static Fn(HashMap<String, String>)),
 }
@@ -94,6 +99,7 @@ impl FromStr for WriteMode {
             "replace" => Ok(WriteMode::Replace),
             "display" => Ok(WriteMode::Display),
             "overwrite" => Ok(WriteMode::Overwrite),
+            "diff" => Ok(WriteMode::Diff),
             _ => Err(()),
         }
     }
diff --git a/src/rustfmt_diff.rs b/src/rustfmt_diff.rs
new file mode 100644
index 00000000000..375cfd661fa
--- /dev/null
+++ b/src/rustfmt_diff.rs
@@ -0,0 +1,109 @@
+use std::collections::VecDeque;
+use diff;
+use term;
+
+pub enum DiffLine {
+    Context(String),
+    Expected(String),
+    Resulting(String),
+}
+
+pub struct Mismatch {
+    pub line_number: u32,
+    pub lines: Vec<DiffLine>,
+}
+
+impl Mismatch {
+    fn new(line_number: u32) -> Mismatch {
+        Mismatch { line_number: line_number, lines: Vec::new() }
+    }
+}
+
+// Produces a diff between the expected output and actual output of rustfmt.
+pub fn make_diff(expected: &str, actual: &str, context_size: usize) -> Vec<Mismatch> {
+    let mut line_number = 1;
+    let mut context_queue: VecDeque<&str> = VecDeque::with_capacity(context_size);
+    let mut lines_since_mismatch = context_size + 1;
+    let mut results = Vec::new();
+    let mut mismatch = Mismatch::new(0);
+
+    for result in diff::lines(expected, actual) {
+        match result {
+            diff::Result::Left(str) => {
+                if lines_since_mismatch >= context_size {
+                    results.push(mismatch);
+                    mismatch = Mismatch::new(line_number - context_queue.len() as u32);
+                }
+
+                while let Some(line) = context_queue.pop_front() {
+                    mismatch.lines.push(DiffLine::Context(line.to_owned()));
+                }
+
+                mismatch.lines.push(DiffLine::Resulting(str.to_owned()));
+                lines_since_mismatch = 0;
+            }
+            diff::Result::Right(str) => {
+                if lines_since_mismatch >= context_size {
+                    results.push(mismatch);
+                    mismatch = Mismatch::new(line_number - context_queue.len() as u32);
+                }
+
+                while let Some(line) = context_queue.pop_front() {
+                    mismatch.lines.push(DiffLine::Context(line.to_owned()));
+                }
+
+                mismatch.lines.push(DiffLine::Expected(str.to_owned()));
+                line_number += 1;
+                lines_since_mismatch = 0;
+            }
+            diff::Result::Both(str, _) => {
+                if context_queue.len() >= context_size {
+                    let _ = context_queue.pop_front();
+                }
+
+                if lines_since_mismatch < context_size {
+                    mismatch.lines.push(DiffLine::Context(str.to_owned()));
+                } else {
+                    context_queue.push_back(str);
+                }
+
+                line_number += 1;
+                lines_since_mismatch += 1;
+            }
+        }
+    }
+
+    results.push(mismatch);
+    results.remove(0);
+
+    results
+}
+
+pub fn print_diff<F>(diff: Vec<Mismatch>, get_section_title: F)
+    where F: Fn(u32) -> String
+{
+    let mut t = term::stdout().unwrap();
+    for mismatch in diff {
+        t.fg(term::color::BRIGHT_WHITE).unwrap();
+        let title = get_section_title(mismatch.line_number);
+        writeln!(t, "{}", title).unwrap();
+
+        for line in mismatch.lines {
+            match line {
+                DiffLine::Context(ref str) => {
+                    t.fg(term::color::WHITE).unwrap();
+                    writeln!(t, " {}⏎", str).unwrap();
+                }
+                DiffLine::Expected(ref str) => {
+                    t.fg(term::color::GREEN).unwrap();
+                    writeln!(t, "+{}⏎", str).unwrap();
+                }
+                DiffLine::Resulting(ref str) => {
+                    t.fg(term::color::RED).unwrap();
+                    writeln!(t, "-{}⏎", str).unwrap();
+                }
+            }
+        }
+    }
+    t.reset().unwrap();
+}
diff --git a/tests/system.rs b/tests/system.rs
index d6ba46c9cf5..b0d96468eca 100644
--- a/tests/system.rs
+++ b/tests/system.rs
@@ -15,12 +15,13 @@ extern crate diff;
 extern crate regex;
 extern crate term;
 
-use std::collections::{VecDeque, HashMap};
+use std::collections::HashMap;
 use std::fs;
 use std::io::{self, Read, BufRead, BufReader};
 use std::thread;
 use rustfmt::*;
 use rustfmt::config::Config;
+use rustfmt::rustfmt_diff::*;
 
 static DIFF_CONTEXT_SIZE: usize = 3;
 
@@ -94,27 +95,7 @@ fn print_mismatches(result: HashMap<String, Vec<Mismatch>>) {
     let mut t = term::stdout().unwrap();
 
     for (file_name, diff) in result {
-        for mismatch in diff {
-            t.fg(term::color::BRIGHT_WHITE).unwrap();
-            writeln!(t, "\nMismatch at {}:{}:", file_name, mismatch.line_number).unwrap();
-
-            for line in mismatch.lines {
-                match line {
-                    DiffLine::Context(ref str) => {
-                        t.fg(term::color::WHITE).unwrap();
-                        writeln!(t, " {}⏎", str).unwrap();
-                    }
-                    DiffLine::Expected(ref str) => {
-                        t.fg(term::color::GREEN).unwrap();
-                        writeln!(t, "+{}⏎", str).unwrap();
-                    }
-                    DiffLine::Resulting(ref str) => {
-                        t.fg(term::color::RED).unwrap();
-                        writeln!(t, "-{}⏎", str).unwrap();
-                    }
-                }
-            }
-        }
+        print_diff(diff, |line_num| format!("\nMismatch at {}:{}:", file_name, line_num));
     }
 
     assert!(t.reset().unwrap());
@@ -206,7 +187,7 @@ fn handle_result(result: HashMap<String, String>) {
         // TODO: speedup by running through bytes iterator
         f.read_to_string(&mut text).ok().expect("Failed reading target.");
         if fmt_text != text {
-            let diff = make_diff(&fmt_text, &text, DIFF_CONTEXT_SIZE);
+            let diff = make_diff(&text, &fmt_text, DIFF_CONTEXT_SIZE);
             failures.insert(file_name, diff);
         }
     }
@@ -226,80 +207,3 @@ fn get_target(file_name: &str, target: Option<&str>) -> String {
         file_name.to_owned()
     }
 }
-
-pub enum DiffLine {
-    Context(String),
-    Expected(String),
-    Resulting(String),
-}
-
-pub struct Mismatch {
-    line_number: u32,
-    pub lines: Vec<DiffLine>,
-}
-
-impl Mismatch {
-    fn new(line_number: u32) -> Mismatch {
-        Mismatch { line_number: line_number, lines: Vec::new() }
-    }
-}
-
-// Produces a diff between the expected output and actual output of rustfmt.
-fn make_diff(expected: &str, actual: &str, context_size: usize) -> Vec<Mismatch> {
-    let mut line_number = 1;
-    let mut context_queue: VecDeque<&str> = VecDeque::with_capacity(context_size);
-    let mut lines_since_mismatch = context_size + 1;
-    let mut results = Vec::new();
-    let mut mismatch = Mismatch::new(0);
-
-    for result in diff::lines(expected, actual) {
-        match result {
-            diff::Result::Left(str) => {
-                if lines_since_mismatch >= context_size {
-                    results.push(mismatch);
-                    mismatch = Mismatch::new(line_number - context_queue.len() as u32);
-                }
-
-                while let Some(line) = context_queue.pop_front() {
-                    mismatch.lines.push(DiffLine::Context(line.to_owned()));
-                }
-
-                mismatch.lines.push(DiffLine::Resulting(str.to_owned()));
-                lines_since_mismatch = 0;
-            }
-            diff::Result::Right(str) => {
-                if lines_since_mismatch >= context_size {
-                    results.push(mismatch);
-                    mismatch = Mismatch::new(line_number - context_queue.len() as u32);
-                }
-
-                while let Some(line) = context_queue.pop_front() {
-                    mismatch.lines.push(DiffLine::Context(line.to_owned()));
-                }
-
-                mismatch.lines.push(DiffLine::Expected(str.to_owned()));
-                line_number += 1;
-                lines_since_mismatch = 0;
-            }
-            diff::Result::Both(str, _) => {
-                if context_queue.len() >= context_size {
-                    let _ = context_queue.pop_front();
-                }
-
-                if lines_since_mismatch < context_size {
-                    mismatch.lines.push(DiffLine::Context(str.to_owned()));
-                } else {
-                    context_queue.push_back(str);
-                }
-
-                line_number += 1;
-                lines_since_mismatch += 1;
-            }
-        }
-    }
-
-    results.push(mismatch);
-    results.remove(0);
-
-    results
-}