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

1 files changed, 109 insertions, 0 deletions

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();
+}