Move non-public API from lib.rs to its own module

src/filemap.rs

@@ -16,7 +16,7 @@ use config::{Config, EmitMode, FileName, Verbosity};
 use rustfmt_diff::{make_diff, output_modified, print_diff};
 
 #[cfg(test)]
-use FileRecord;
+use formatting::FileRecord;
 
 // Append a newline to the end of each file.
 pub fn append_newline(s: &mut String) {

src/formatting.rs

@@ -0,0 +1,593 @@
+// High level formatting functions.
+
+use std::collections::HashMap;
+use std::io::{self, Write};
+use std::panic::{catch_unwind, AssertUnwindSafe};
+use std::rc::Rc;
+use std::time::Duration;
+
+use syntax::ast;
+use syntax::codemap::{CodeMap, FilePathMapping, Span};
+use syntax::errors::emitter::{ColorConfig, EmitterWriter};
+use syntax::errors::{DiagnosticBuilder, Handler};
+use syntax::parse::{self, ParseSess};
+
+use comment::{CharClasses, FullCodeCharKind};
+use issues::BadIssueSeeker;
+use visitor::{FmtVisitor, SnippetProvider};
+use {filemap, modules, ErrorKind, FormatReport, Input};
+
+use config::summary::Summary;
+use config::{Config, FileName, NewlineStyle, Verbosity};
+
+// A map of the files of a crate, with their new content
+pub(crate) type FileMap = Vec<FileRecord>;
+
+pub(crate) type FileRecord = (FileName, String);
+
+pub(crate) struct FormattingError {
+    pub(crate) line: usize,
+    pub(crate) kind: ErrorKind,
+    is_comment: bool,
+    is_string: bool,
+    pub(crate) line_buffer: String,
+}
+
+impl FormattingError {
+    pub(crate) fn from_span(span: &Span, codemap: &CodeMap, kind: ErrorKind) -> FormattingError {
+        FormattingError {
+            line: codemap.lookup_char_pos(span.lo()).line,
+            is_comment: kind.is_comment(),
+            kind,
+            is_string: false,
+            line_buffer: codemap
+                .span_to_lines(*span)
+                .ok()
+                .and_then(|fl| {
+                    fl.file
+                        .get_line(fl.lines[0].line_index)
+                        .map(|l| l.into_owned())
+                })
+                .unwrap_or_else(|| String::new()),
+        }
+    }
+
+    pub(crate) fn msg_prefix(&self) -> &str {
+        match self.kind {
+            ErrorKind::LineOverflow(..)
+            | ErrorKind::TrailingWhitespace
+            | ErrorKind::IoError(_)
+            | ErrorKind::ParseError
+            | ErrorKind::LostComment => "internal error:",
+            ErrorKind::LicenseCheck | ErrorKind::BadAttr | ErrorKind::VersionMismatch => "error:",
+            ErrorKind::BadIssue(_) | ErrorKind::DeprecatedAttr => "warning:",
+        }
+    }
+
+    pub(crate) fn msg_suffix(&self) -> &str {
+        if self.is_comment || self.is_string {
+            "set `error_on_unformatted = false` to suppress \
+             the warning against comments or string literals\n"
+        } else {
+            ""
+        }
+    }
+
+    // (space, target)
+    pub(crate) fn format_len(&self) -> (usize, usize) {
+        match self.kind {
+            ErrorKind::LineOverflow(found, max) => (max, found - max),
+            ErrorKind::TrailingWhitespace
+            | ErrorKind::DeprecatedAttr
+            | ErrorKind::BadAttr
+            | ErrorKind::LostComment => {
+                let trailing_ws_start = self
+                    .line_buffer
+                    .rfind(|c: char| !c.is_whitespace())
+                    .map(|pos| pos + 1)
+                    .unwrap_or(0);
+                (
+                    trailing_ws_start,
+                    self.line_buffer.len() - trailing_ws_start,
+                )
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+
+pub(crate) type FormatErrorMap = HashMap<FileName, Vec<FormattingError>>;
+
+#[derive(Default, Debug)]
+pub(crate) struct ReportedErrors {
+    pub(crate) has_operational_errors: bool,
+    pub(crate) has_check_errors: bool,
+}
+
+fn should_emit_verbose<F>(path: &FileName, config: &Config, f: F)
+where
+    F: Fn(),
+{
+    if config.verbose() == Verbosity::Verbose && path != &FileName::Stdin {
+        f();
+    }
+}
+
+// Formatting which depends on the AST.
+fn format_ast<F>(
+    krate: &ast::Crate,
+    parse_session: &mut ParseSess,
+    main_file: &FileName,
+    config: &Config,
+    report: FormatReport,
+    mut after_file: F,
+) -> Result<(FileMap, bool, bool), io::Error>
+where
+    F: FnMut(&FileName, &mut String, &[(usize, usize)], &FormatReport) -> Result<bool, io::Error>,
+{
+    let mut result = FileMap::new();
+    // diff mode: check if any files are differing
+    let mut has_diff = false;
+    let mut has_macro_rewrite_failure = false;
+
+    let skip_children = config.skip_children();
+    for (path, module) in modules::list_files(krate, parse_session.codemap())? {
+        if (skip_children && path != *main_file) || config.ignore().skip_file(&path) {
+            continue;
+        }
+        should_emit_verbose(&path, config, || println!("Formatting {}", path));
+        let filemap = parse_session
+            .codemap()
+            .lookup_char_pos(module.inner.lo())
+            .file;
+        let big_snippet = filemap.src.as_ref().unwrap();
+        let snippet_provider = SnippetProvider::new(filemap.start_pos, big_snippet);
+        let mut visitor =
+            FmtVisitor::from_codemap(parse_session, config, &snippet_provider, report.clone());
+        // Format inner attributes if available.
+        if !krate.attrs.is_empty() && path == *main_file {
+            visitor.skip_empty_lines(filemap.end_pos);
+            if visitor.visit_attrs(&krate.attrs, ast::AttrStyle::Inner) {
+                visitor.push_rewrite(module.inner, None);
+            } else {
+                visitor.format_separate_mod(module, &*filemap);
+            }
+        } else {
+            visitor.last_pos = filemap.start_pos;
+            visitor.skip_empty_lines(filemap.end_pos);
+            visitor.format_separate_mod(module, &*filemap);
+        };
+
+        debug_assert_eq!(
+            visitor.line_number,
+            ::utils::count_newlines(&visitor.buffer)
+        );
+
+        has_diff |= match after_file(&path, &mut visitor.buffer, &visitor.skipped_range, &report) {
+            Ok(result) => result,
+            Err(e) => {
+                // Create a new error with path_str to help users see which files failed
+                let err_msg = format!("{}: {}", path, e);
+                return Err(io::Error::new(e.kind(), err_msg));
+            }
+        };
+
+        has_macro_rewrite_failure |= visitor.macro_rewrite_failure;
+
+        result.push((path.clone(), visitor.buffer));
+    }
+
+    Ok((result, has_diff, has_macro_rewrite_failure))
+}
+
+/// Returns true if the line with the given line number was skipped by `#[rustfmt::skip]`.
+fn is_skipped_line(line_number: usize, skipped_range: &[(usize, usize)]) -> bool {
+    skipped_range
+        .iter()
+        .any(|&(lo, hi)| lo <= line_number && line_number <= hi)
+}
+
+fn should_report_error(
+    config: &Config,
+    char_kind: FullCodeCharKind,
+    is_string: bool,
+    error_kind: &ErrorKind,
+) -> bool {
+    let allow_error_report = if char_kind.is_comment() || is_string || error_kind.is_comment() {
+        config.error_on_unformatted()
+    } else {
+        true
+    };
+
+    match error_kind {
+        ErrorKind::LineOverflow(..) => config.error_on_line_overflow() && allow_error_report,
+        ErrorKind::TrailingWhitespace | ErrorKind::LostComment => allow_error_report,
+        _ => true,
+    }
+}
+
+// Formatting done on a char by char or line by line basis.
+// FIXME(#20) other stuff for parity with make tidy
+fn format_lines(
+    text: &mut String,
+    name: &FileName,
+    skipped_range: &[(usize, usize)],
+    config: &Config,
+    report: &FormatReport,
+) {
+    let mut last_was_space = false;
+    let mut line_len = 0;
+    let mut cur_line = 1;
+    let mut newline_count = 0;
+    let mut errors = vec![];
+    let mut issue_seeker = BadIssueSeeker::new(config.report_todo(), config.report_fixme());
+    let mut line_buffer = String::with_capacity(config.max_width() * 2);
+    let mut is_string = false; // true if the current line contains a string literal.
+    let mut format_line = config.file_lines().contains_line(name, cur_line);
+    let allow_issue_seek = !issue_seeker.is_disabled();
+
+    // Check license.
+    if let Some(ref license_template) = config.license_template {
+        if !license_template.is_match(text) {
+            errors.push(FormattingError {
+                line: cur_line,
+                kind: ErrorKind::LicenseCheck,
+                is_comment: false,
+                is_string: false,
+                line_buffer: String::new(),
+            });
+        }
+    }
+
+    // Iterate over the chars in the file map.
+    for (kind, c) in CharClasses::new(text.chars()) {
+        if c == '\r' {
+            continue;
+        }
+
+        if allow_issue_seek && format_line {
+            // Add warnings for bad todos/ fixmes
+            if let Some(issue) = issue_seeker.inspect(c) {
+                errors.push(FormattingError {
+                    line: cur_line,
+                    kind: ErrorKind::BadIssue(issue),
+                    is_comment: false,
+                    is_string: false,
+                    line_buffer: String::new(),
+                });
+            }
+        }
+
+        if c == '\n' {
+            if format_line {
+                // Check for (and record) trailing whitespace.
+                if last_was_space {
+                    if should_report_error(config, kind, is_string, &ErrorKind::TrailingWhitespace)
+                        && !is_skipped_line(cur_line, skipped_range)
+                    {
+                        errors.push(FormattingError {
+                            line: cur_line,
+                            kind: ErrorKind::TrailingWhitespace,
+                            is_comment: kind.is_comment(),
+                            is_string: kind.is_string(),
+                            line_buffer: line_buffer.clone(),
+                        });
+                    }
+                    line_len -= 1;
+                }
+
+                // Check for any line width errors we couldn't correct.
+                let error_kind = ErrorKind::LineOverflow(line_len, config.max_width());
+                if line_len > config.max_width()
+                    && !is_skipped_line(cur_line, skipped_range)
+                    && should_report_error(config, kind, is_string, &error_kind)
+                {
+                    errors.push(FormattingError {
+                        line: cur_line,
+                        kind: error_kind,
+                        is_comment: kind.is_comment(),
+                        is_string,
+                        line_buffer: line_buffer.clone(),
+                    });
+                }
+            }
+
+            line_len = 0;
+            cur_line += 1;
+            format_line = config.file_lines().contains_line(name, cur_line);
+            newline_count += 1;
+            last_was_space = false;
+            line_buffer.clear();
+            is_string = false;
+        } else {
+            newline_count = 0;
+            line_len += if c == '\t' { config.tab_spaces() } else { 1 };
+            last_was_space = c.is_whitespace();
+            line_buffer.push(c);
+            if kind.is_string() {
+                is_string = true;
+            }
+        }
+    }
+
+    if newline_count > 1 {
+        debug!("track truncate: {} {}", text.len(), newline_count);
+        let line = text.len() - newline_count + 1;
+        text.truncate(line);
+    }
+
+    report.append(name.clone(), errors);
+}
+
+fn parse_input<'sess>(
+    input: Input,
+    parse_session: &'sess ParseSess,
+    config: &Config,
+) -> Result<ast::Crate, ParseError<'sess>> {
+    let mut parser = match input {
+        Input::File(file) => parse::new_parser_from_file(parse_session, &file),
+        Input::Text(text) => parse::new_parser_from_source_str(
+            parse_session,
+            syntax::codemap::FileName::Custom("stdin".to_owned()),
+            text,
+        ),
+    };
+
+    parser.cfg_mods = false;
+    if config.skip_children() {
+        parser.recurse_into_file_modules = false;
+    }
+
+    let mut parser = AssertUnwindSafe(parser);
+    let result = catch_unwind(move || parser.0.parse_crate_mod());
+
+    match result {
+        Ok(Ok(c)) => {
+            if parse_session.span_diagnostic.has_errors() {
+                // Bail out if the parser recovered from an error.
+                Err(ParseError::Recovered)
+            } else {
+                Ok(c)
+            }
+        }
+        Ok(Err(e)) => Err(ParseError::Error(e)),
+        Err(_) => Err(ParseError::Panic),
+    }
+}
+
+/// All the ways that parsing can fail.
+enum ParseError<'sess> {
+    /// There was an error, but the parser recovered.
+    Recovered,
+    /// There was an error (supplied) and parsing failed.
+    Error(DiagnosticBuilder<'sess>),
+    /// The parser panicked.
+    Panic,
+}
+
+pub(crate) fn format_input_inner<T: Write>(
+    input: Input,
+    config: &Config,
+    mut out: Option<&mut T>,
+) -> Result<(Summary, FileMap, FormatReport), (ErrorKind, Summary)> {
+    syntax_pos::hygiene::set_default_edition(config.edition().to_libsyntax_pos_edition());
+    let mut summary = Summary::default();
+    if config.disable_all_formatting() {
+        // When the input is from stdin, echo back the input.
+        if let Input::Text(ref buf) = input {
+            if let Err(e) = io::stdout().write_all(buf.as_bytes()) {
+                return Err((From::from(e), summary));
+            }
+        }
+        return Ok((summary, FileMap::new(), FormatReport::new()));
+    }
+    let codemap = Rc::new(CodeMap::new(FilePathMapping::empty()));
+
+    let tty_handler = if config.hide_parse_errors() {
+        let silent_emitter = Box::new(EmitterWriter::new(
+            Box::new(Vec::new()),
+            Some(codemap.clone()),
+            false,
+            false,
+        ));
+        Handler::with_emitter(true, false, silent_emitter)
+    } else {
+        let supports_color = term::stderr().map_or(false, |term| term.supports_color());
+        let color_cfg = if supports_color {
+            ColorConfig::Auto
+        } else {
+            ColorConfig::Never
+        };
+        Handler::with_tty_emitter(color_cfg, true, false, Some(codemap.clone()))
+    };
+    let mut parse_session = ParseSess::with_span_handler(tty_handler, codemap.clone());
+
+    let main_file = match input {
+        Input::File(ref file) => FileName::Real(file.clone()),
+        Input::Text(..) => FileName::Stdin,
+    };
+
+    let krate = match parse_input(input, &parse_session, config) {
+        Ok(krate) => krate,
+        Err(err) => {
+            match err {
+                ParseError::Error(mut diagnostic) => diagnostic.emit(),
+                ParseError::Panic => {
+                    // Note that if you see this message and want more information,
+                    // then go to `parse_input` and run the parse function without
+                    // `catch_unwind` so rustfmt panics and you can get a backtrace.
+                    should_emit_verbose(&main_file, config, || {
+                        println!("The Rust parser panicked")
+                    });
+                }
+                ParseError::Recovered => {}
+            }
+            summary.add_parsing_error();
+            return Err((ErrorKind::ParseError, summary));
+        }
+    };
+
+    summary.mark_parse_time();
+
+    // Suppress error output after parsing.
+    let silent_emitter = Box::new(EmitterWriter::new(
+        Box::new(Vec::new()),
+        Some(codemap.clone()),
+        false,
+        false,
+    ));
+    parse_session.span_diagnostic = Handler::with_emitter(true, false, silent_emitter);
+
+    let report = FormatReport::new();
+
+    let format_result = format_ast(
+        &krate,
+        &mut parse_session,
+        &main_file,
+        config,
+        report.clone(),
+        |file_name, file, skipped_range, report| {
+            // For some reason, the codemap does not include terminating
+            // newlines so we must add one on for each file. This is sad.
+            filemap::append_newline(file);
+
+            format_lines(file, file_name, skipped_range, config, report);
+            replace_with_system_newlines(file, config);
+
+            if let Some(ref mut out) = out {
+                return filemap::write_file(file, file_name, out, config);
+            }
+            Ok(false)
+        },
+    );
+
+    summary.mark_format_time();
+
+    should_emit_verbose(&main_file, config, || {
+        fn duration_to_f32(d: Duration) -> f32 {
+            d.as_secs() as f32 + d.subsec_nanos() as f32 / 1_000_000_000f32
+        }
+
+        println!(
+            "Spent {0:.3} secs in the parsing phase, and {1:.3} secs in the formatting phase",
+            duration_to_f32(summary.get_parse_time().unwrap()),
+            duration_to_f32(summary.get_format_time().unwrap()),
+        )
+    });
+
+    {
+        let report_errs = &report.internal.borrow().1;
+        if report_errs.has_check_errors {
+            summary.add_check_error();
+        }
+        if report_errs.has_operational_errors {
+            summary.add_operational_error();
+        }
+    }
+
+    match format_result {
+        Ok((file_map, has_diff, has_macro_rewrite_failure)) => {
+            if report.has_warnings() {
+                summary.add_formatting_error();
+            }
+
+            if has_diff {
+                summary.add_diff();
+            }
+
+            if has_macro_rewrite_failure {
+                summary.add_macro_foramt_failure();
+            }
+
+            Ok((summary, file_map, report))
+        }
+        Err(e) => Err((From::from(e), summary)),
+    }
+}
+
+fn replace_with_system_newlines(text: &mut String, config: &Config) -> () {
+    let style = if config.newline_style() == NewlineStyle::Native {
+        if cfg!(windows) {
+            NewlineStyle::Windows
+        } else {
+            NewlineStyle::Unix
+        }
+    } else {
+        config.newline_style()
+    };
+
+    match style {
+        NewlineStyle::Unix => return,
+        NewlineStyle::Windows => {
+            let mut transformed = String::with_capacity(text.capacity());
+            for c in text.chars() {
+                match c {
+                    '\n' => transformed.push_str("\r\n"),
+                    '\r' => continue,
+                    c => transformed.push(c),
+                }
+            }
+            *text = transformed;
+        }
+        NewlineStyle::Native => unreachable!(),
+    }
+}
+
+/// A single span of changed lines, with 0 or more removed lines
+/// and a vector of 0 or more inserted lines.
+#[derive(Debug, PartialEq, Eq)]
+pub(crate) struct ModifiedChunk {
+    /// The first to be removed from the original text
+    pub line_number_orig: u32,
+    /// The number of lines which have been replaced
+    pub lines_removed: u32,
+    /// The new lines
+    pub lines: Vec<String>,
+}
+
+/// Set of changed sections of a file.
+#[derive(Debug, PartialEq, Eq)]
+pub(crate) struct ModifiedLines {
+    /// The set of changed chunks.
+    pub chunks: Vec<ModifiedChunk>,
+}
+
+/// Format a file and return a `ModifiedLines` data structure describing
+/// the changed ranges of lines.
+#[cfg(test)]
+pub(crate) fn get_modified_lines(
+    input: Input,
+    config: &Config,
+) -> Result<ModifiedLines, (ErrorKind, Summary)> {
+    use std::io::BufRead;
+
+    let mut data = Vec::new();
+
+    let mut config = config.clone();
+    config.set().emit_mode(::config::EmitMode::ModifiedLines);
+    ::format_input(input, &config, Some(&mut data))?;
+
+    let mut lines = data.lines();
+    let mut chunks = Vec::new();
+    while let Some(Ok(header)) = lines.next() {
+        // Parse the header line
+        let values: Vec<_> = header
+            .split(' ')
+            .map(|s| s.parse::<u32>().unwrap())
+            .collect();
+        assert_eq!(values.len(), 3);
+        let line_number_orig = values[0];
+        let lines_removed = values[1];
+        let num_added = values[2];
+        let mut added_lines = Vec::new();
+        for _ in 0..num_added {
+            added_lines.push(lines.next().unwrap().unwrap());
+        }
+        chunks.push(ModifiedChunk {
+            line_number_orig,
+            lines_removed,
+            lines: added_lines,
+        });
+    }
+    Ok(ModifiedLines { chunks })
+}

src/lib.rs

@@ -41,22 +41,15 @@ use std::cell::RefCell;
 use std::collections::HashMap;
 use std::fmt;
 use std::io::{self, Write};
-use std::panic::{catch_unwind, AssertUnwindSafe};
 use std::path::PathBuf;
 use std::rc::Rc;
-use std::time::Duration;
-
 use syntax::ast;
-use syntax::codemap::{CodeMap, FilePathMapping, Span};
-use syntax::errors::emitter::{ColorConfig, EmitterWriter};
-use syntax::errors::{DiagnosticBuilder, Handler};
-use syntax::parse::{self, ParseSess};
 
-use comment::{CharClasses, FullCodeCharKind, LineClasses};
+use comment::LineClasses;
 use failure::Fail;
-use issues::{BadIssueSeeker, Issue};
+use formatting::{format_input_inner, FormatErrorMap, FormattingError, ReportedErrors};
+use issues::Issue;
 use shape::Indent;
-use visitor::{FmtVisitor, SnippetProvider};
 
 pub use checkstyle::{footer as checkstyle_footer, header as checkstyle_header};
 pub use config::summary::Summary;
@@ -77,6 +70,7 @@ mod comment;
 pub(crate) mod config;
 mod expr;
 pub(crate) mod filemap;
+pub(crate) mod formatting;
 mod imports;
 mod issues;
 mod items;
@@ -100,11 +94,6 @@ mod types;
 mod vertical;
 pub(crate) mod visitor;
 
-// A map of the files of a crate, with their new content
-pub(crate) type FileMap = Vec<FileRecord>;
-
-pub(crate) type FileRecord = (FileName, String);
-
 /// The various errors that can occur during formatting. Note that not all of
 /// these can currently be propagated to clients.
 #[derive(Fail, Debug)]
@@ -162,76 +151,6 @@ impl From<io::Error> for ErrorKind {
     }
 }
 
-struct FormattingError {
-    line: usize,
-    kind: ErrorKind,
-    is_comment: bool,
-    is_string: bool,
-    line_buffer: String,
-}
-
-impl FormattingError {
-    fn from_span(span: &Span, codemap: &CodeMap, kind: ErrorKind) -> FormattingError {
-        FormattingError {
-            line: codemap.lookup_char_pos(span.lo()).line,
-            is_comment: kind.is_comment(),
-            kind,
-            is_string: false,
-            line_buffer: codemap
-                .span_to_lines(*span)
-                .ok()
-                .and_then(|fl| {
-                    fl.file
-                        .get_line(fl.lines[0].line_index)
-                        .map(|l| l.into_owned())
-                })
-                .unwrap_or_else(|| String::new()),
-        }
-    }
-    fn msg_prefix(&self) -> &str {
-        match self.kind {
-            ErrorKind::LineOverflow(..)
-            | ErrorKind::TrailingWhitespace
-            | ErrorKind::IoError(_)
-            | ErrorKind::ParseError
-            | ErrorKind::LostComment => "internal error:",
-            ErrorKind::LicenseCheck | ErrorKind::BadAttr | ErrorKind::VersionMismatch => "error:",
-            ErrorKind::BadIssue(_) | ErrorKind::DeprecatedAttr => "warning:",
-        }
-    }
-
-    fn msg_suffix(&self) -> &str {
-        if self.is_comment || self.is_string {
-            "set `error_on_unformatted = false` to suppress \
-             the warning against comments or string literals\n"
-        } else {
-            ""
-        }
-    }
-
-    // (space, target)
-    fn format_len(&self) -> (usize, usize) {
-        match self.kind {
-            ErrorKind::LineOverflow(found, max) => (max, found - max),
-            ErrorKind::TrailingWhitespace
-            | ErrorKind::DeprecatedAttr
-            | ErrorKind::BadAttr
-            | ErrorKind::LostComment => {
-                let trailing_ws_start = self
-                    .line_buffer
-                    .rfind(|c: char| !c.is_whitespace())
-                    .map(|pos| pos + 1)
-                    .unwrap_or(0);
-                (
-                    trailing_ws_start,
-                    self.line_buffer.len() - trailing_ws_start,
-                )
-            }
-            _ => unreachable!(),
-        }
-    }
-}
-
 /// Reports on any issues that occurred during a run of Rustfmt.
 ///
 /// Can be reported to the user via its `Display` implementation of `print_fancy`.
@@ -241,14 +160,6 @@ pub struct FormatReport {
     internal: Rc<RefCell<(FormatErrorMap, ReportedErrors)>>,
 }
 
-type FormatErrorMap = HashMap<FileName, Vec<FormattingError>>;
-
-#[derive(Default, Debug)]
-struct ReportedErrors {
-    has_operational_errors: bool,
-    has_check_errors: bool,
-}
-
 impl FormatReport {
     fn new() -> FormatReport {
         FormatReport {
@@ -336,7 +247,7 @@ impl FormatReport {
                     t.attr(term::Attr::Bold)?;
                     write!(t, "{}| ", prefix_spaces)?;
                     t.fg(term::color::RED)?;
-                    writeln!(t, "{}", target_str(space_len, target_len))?;
+                    writeln!(t, "{}", FormatReport::target_str(space_len, target_len))?;
                     t.reset()?;
                 }
 
@@ -367,12 +278,12 @@ impl FormatReport {
 
         Ok(())
     }
-}
 
-fn target_str(space_len: usize, target_len: usize) -> String {
-    let empty_line = " ".repeat(space_len);
-    let overflowed = "^".repeat(target_len);
-    empty_line + &overflowed
+    fn target_str(space_len: usize, target_len: usize) -> String {
+        let empty_line = " ".repeat(space_len);
+        let overflowed = "^".repeat(target_len);
+        empty_line + &overflowed
+    }
 }
 
 impl fmt::Display for FormatReport {
@@ -393,7 +304,7 @@ impl fmt::Display for FormatReport {
                         error.line,
                         error.line_buffer,
                         prefix_spaces,
-                        target_str(space_len, target_len)
+                        FormatReport::target_str(space_len, target_len)
                     )
                 };
 
@@ -428,267 +339,6 @@ impl fmt::Display for FormatReport {
     }
 }
 
-fn should_emit_verbose<F>(path: &FileName, config: &Config, f: F)
-where
-    F: Fn(),
-{
-    if config.verbose() == Verbosity::Verbose && path != &FileName::Stdin {
-        f();
-    }
-}
-
-// Formatting which depends on the AST.
-fn format_ast<F>(
-    krate: &ast::Crate,
-    parse_session: &mut ParseSess,
-    main_file: &FileName,
-    config: &Config,
-    report: FormatReport,
-    mut after_file: F,
-) -> Result<(FileMap, bool, bool), io::Error>
-where
-    F: FnMut(&FileName, &mut String, &[(usize, usize)], &FormatReport) -> Result<bool, io::Error>,
-{
-    let mut result = FileMap::new();
-    // diff mode: check if any files are differing
-    let mut has_diff = false;
-    let mut has_macro_rewrite_failure = false;
-
-    let skip_children = config.skip_children();
-    for (path, module) in modules::list_files(krate, parse_session.codemap())? {
-        if (skip_children && path != *main_file) || config.ignore().skip_file(&path) {
-            continue;
-        }
-        should_emit_verbose(&path, config, || println!("Formatting {}", path));
-        let filemap = parse_session
-            .codemap()
-            .lookup_char_pos(module.inner.lo())
-            .file;
-        let big_snippet = filemap.src.as_ref().unwrap();
-        let snippet_provider = SnippetProvider::new(filemap.start_pos, big_snippet);
-        let mut visitor =
-            FmtVisitor::from_codemap(parse_session, config, &snippet_provider, report.clone());
-        // Format inner attributes if available.
-        if !krate.attrs.is_empty() && path == *main_file {
-            visitor.skip_empty_lines(filemap.end_pos);
-            if visitor.visit_attrs(&krate.attrs, ast::AttrStyle::Inner) {
-                visitor.push_rewrite(module.inner, None);
-            } else {
-                visitor.format_separate_mod(module, &*filemap);
-            }
-        } else {
-            visitor.last_pos = filemap.start_pos;
-            visitor.skip_empty_lines(filemap.end_pos);
-            visitor.format_separate_mod(module, &*filemap);
-        };
-
-        debug_assert_eq!(
-            visitor.line_number,
-            ::utils::count_newlines(&visitor.buffer)
-        );
-
-        has_diff |= match after_file(&path, &mut visitor.buffer, &visitor.skipped_range, &report) {
-            Ok(result) => result,
-            Err(e) => {
-                // Create a new error with path_str to help users see which files failed
-                let err_msg = format!("{}: {}", path, e);
-                return Err(io::Error::new(e.kind(), err_msg));
-            }
-        };
-
-        has_macro_rewrite_failure |= visitor.macro_rewrite_failure;
-
-        result.push((path.clone(), visitor.buffer));
-    }
-
-    Ok((result, has_diff, has_macro_rewrite_failure))
-}
-
-/// Returns true if the line with the given line number was skipped by `#[rustfmt::skip]`.
-fn is_skipped_line(line_number: usize, skipped_range: &[(usize, usize)]) -> bool {
-    skipped_range
-        .iter()
-        .any(|&(lo, hi)| lo <= line_number && line_number <= hi)
-}
-
-fn should_report_error(
-    config: &Config,
-    char_kind: FullCodeCharKind,
-    is_string: bool,
-    error_kind: &ErrorKind,
-) -> bool {
-    let allow_error_report = if char_kind.is_comment() || is_string || error_kind.is_comment() {
-        config.error_on_unformatted()
-    } else {
-        true
-    };
-
-    match error_kind {
-        ErrorKind::LineOverflow(..) => config.error_on_line_overflow() && allow_error_report,
-        ErrorKind::TrailingWhitespace | ErrorKind::LostComment => allow_error_report,
-        _ => true,
-    }
-}
-
-// Formatting done on a char by char or line by line basis.
-// FIXME(#20) other stuff for parity with make tidy
-fn format_lines(
-    text: &mut String,
-    name: &FileName,
-    skipped_range: &[(usize, usize)],
-    config: &Config,
-    report: &FormatReport,
-) {
-    let mut last_was_space = false;
-    let mut line_len = 0;
-    let mut cur_line = 1;
-    let mut newline_count = 0;
-    let mut errors = vec![];
-    let mut issue_seeker = BadIssueSeeker::new(config.report_todo(), config.report_fixme());
-    let mut line_buffer = String::with_capacity(config.max_width() * 2);
-    let mut is_string = false; // true if the current line contains a string literal.
-    let mut format_line = config.file_lines().contains_line(name, cur_line);
-    let allow_issue_seek = !issue_seeker.is_disabled();
-
-    // Check license.
-    if let Some(ref license_template) = config.license_template {
-        if !license_template.is_match(text) {
-            errors.push(FormattingError {
-                line: cur_line,
-                kind: ErrorKind::LicenseCheck,
-                is_comment: false,
-                is_string: false,
-                line_buffer: String::new(),
-            });
-        }
-    }
-
-    // Iterate over the chars in the file map.
-    for (kind, c) in CharClasses::new(text.chars()) {
-        if c == '\r' {
-            continue;
-        }
-
-        if allow_issue_seek && format_line {
-            // Add warnings for bad todos/ fixmes
-            if let Some(issue) = issue_seeker.inspect(c) {
-                errors.push(FormattingError {
-                    line: cur_line,
-                    kind: ErrorKind::BadIssue(issue),
-                    is_comment: false,
-                    is_string: false,
-                    line_buffer: String::new(),
-                });
-            }
-        }
-
-        if c == '\n' {
-            if format_line {
-                // Check for (and record) trailing whitespace.
-                if last_was_space {
-                    if should_report_error(config, kind, is_string, &ErrorKind::TrailingWhitespace)
-                        && !is_skipped_line(cur_line, skipped_range)
-                    {
-                        errors.push(FormattingError {
-                            line: cur_line,
-                            kind: ErrorKind::TrailingWhitespace,
-                            is_comment: kind.is_comment(),
-                            is_string: kind.is_string(),
-                            line_buffer: line_buffer.clone(),
-                        });
-                    }
-                    line_len -= 1;
-                }
-
-                // Check for any line width errors we couldn't correct.
-                let error_kind = ErrorKind::LineOverflow(line_len, config.max_width());
-                if line_len > config.max_width()
-                    && !is_skipped_line(cur_line, skipped_range)
-                    && should_report_error(config, kind, is_string, &error_kind)
-                {
-                    errors.push(FormattingError {
-                        line: cur_line,
-                        kind: error_kind,
-                        is_comment: kind.is_comment(),
-                        is_string,
-                        line_buffer: line_buffer.clone(),
-                    });
-                }
-            }
-
-            line_len = 0;
-            cur_line += 1;
-            format_line = config.file_lines().contains_line(name, cur_line);
-            newline_count += 1;
-            last_was_space = false;
-            line_buffer.clear();
-            is_string = false;
-        } else {
-            newline_count = 0;
-            line_len += if c == '\t' { config.tab_spaces() } else { 1 };
-            last_was_space = c.is_whitespace();
-            line_buffer.push(c);
-            if kind.is_string() {
-                is_string = true;
-            }
-        }
-    }
-
-    if newline_count > 1 {
-        debug!("track truncate: {} {}", text.len(), newline_count);
-        let line = text.len() - newline_count + 1;
-        text.truncate(line);
-    }
-
-    report.append(name.clone(), errors);
-}
-
-fn parse_input<'sess>(
-    input: Input,
-    parse_session: &'sess ParseSess,
-    config: &Config,
-) -> Result<ast::Crate, ParseError<'sess>> {
-    let mut parser = match input {
-        Input::File(file) => parse::new_parser_from_file(parse_session, &file),
-        Input::Text(text) => parse::new_parser_from_source_str(
-            parse_session,
-            syntax::codemap::FileName::Custom("stdin".to_owned()),
-            text,
-        ),
-    };
-
-    parser.cfg_mods = false;
-    if config.skip_children() {
-        parser.recurse_into_file_modules = false;
-    }
-
-    let mut parser = AssertUnwindSafe(parser);
-    let result = catch_unwind(move || parser.0.parse_crate_mod());
-
-    match result {
-        Ok(Ok(c)) => {
-            if parse_session.span_diagnostic.has_errors() {
-                // Bail out if the parser recovered from an error.
-                Err(ParseError::Recovered)
-            } else {
-                Ok(c)
-            }
-        }
-        Ok(Err(e)) => Err(ParseError::Error(e)),
-        Err(_) => Err(ParseError::Panic),
-    }
-}
-
-/// All the ways that parsing can fail.
-enum ParseError<'sess> {
-    /// There was an error, but the parser recovered.
-    Recovered,
-    /// There was an error (supplied) and parsing failed.
-    Error(DiagnosticBuilder<'sess>),
-    /// The parser panicked.
-    Panic,
-}
-
 /// Format the given snippet. The snippet is expected to be *complete* code.
 /// When we cannot parse the given snippet, this function returns `None`.
 fn format_snippet(snippet: &str, config: &Config) -> Option<String> {
@@ -707,30 +357,30 @@ fn format_snippet(snippet: &str, config: &Config) -> Option<String> {
     }
 }
 
-const FN_MAIN_PREFIX: &str = "fn main() {\n";
-
-fn enclose_in_main_block(s: &str, config: &Config) -> String {
-    let indent = Indent::from_width(config, config.tab_spaces());
-    let mut result = String::with_capacity(s.len() * 2);
-    result.push_str(FN_MAIN_PREFIX);
-    let mut need_indent = true;
-    for (kind, line) in LineClasses::new(s) {
-        if need_indent {
-            result.push_str(&indent.to_string(config));
-        }
-        result.push_str(&line);
-        result.push('\n');
-        need_indent = !kind.is_string() || line.ends_with('\\');
-    }
-    result.push('}');
-    result
-}
-
 /// Format the given code block. Mainly targeted for code block in comment.
 /// The code block may be incomplete (i.e. parser may be unable to parse it).
 /// To avoid panic in parser, we wrap the code block with a dummy function.
 /// The returned code block does *not* end with newline.
 fn format_code_block(code_snippet: &str, config: &Config) -> Option<String> {
+    const FN_MAIN_PREFIX: &str = "fn main() {\n";
+
+    fn enclose_in_main_block(s: &str, config: &Config) -> String {
+        let indent = Indent::from_width(config, config.tab_spaces());
+        let mut result = String::with_capacity(s.len() * 2);
+        result.push_str(FN_MAIN_PREFIX);
+        let mut need_indent = true;
+        for (kind, line) in LineClasses::new(s) {
+            if need_indent {
+                result.push_str(&indent.to_string(config));
+            }
+            result.push_str(&line);
+            result.push('\n');
+            need_indent = !kind.is_string() || line.ends_with('\\');
+        }
+        result.push('}');
+        result
+    }
+
     // Wrap the given code block with `fn main()` if it does not have one.
     let snippet = enclose_in_main_block(code_snippet, config);
     let mut result = String::with_capacity(snippet.len());
@@ -806,236 +456,9 @@ pub fn format_input<T: Write>(
     syntax::with_globals(|| format_input_inner(input, config, out)).map(|tup| (tup.0, tup.2))
 }
 
-fn format_input_inner<T: Write>(
-    input: Input,
-    config: &Config,
-    mut out: Option<&mut T>,
-) -> Result<(Summary, FileMap, FormatReport), (ErrorKind, Summary)> {
-    syntax_pos::hygiene::set_default_edition(config.edition().to_libsyntax_pos_edition());
-    let mut summary = Summary::default();
-    if config.disable_all_formatting() {
-        // When the input is from stdin, echo back the input.
-        if let Input::Text(ref buf) = input {
-            if let Err(e) = io::stdout().write_all(buf.as_bytes()) {
-                return Err((From::from(e), summary));
-            }
-        }
-        return Ok((summary, FileMap::new(), FormatReport::new()));
-    }
-    let codemap = Rc::new(CodeMap::new(FilePathMapping::empty()));
-
-    let tty_handler = if config.hide_parse_errors() {
-        let silent_emitter = Box::new(EmitterWriter::new(
-            Box::new(Vec::new()),
-            Some(codemap.clone()),
-            false,
-            false,
-        ));
-        Handler::with_emitter(true, false, silent_emitter)
-    } else {
-        let supports_color = term::stderr().map_or(false, |term| term.supports_color());
-        let color_cfg = if supports_color {
-            ColorConfig::Auto
-        } else {
-            ColorConfig::Never
-        };
-        Handler::with_tty_emitter(color_cfg, true, false, Some(codemap.clone()))
-    };
-    let mut parse_session = ParseSess::with_span_handler(tty_handler, codemap.clone());
-
-    let main_file = match input {
-        Input::File(ref file) => FileName::Real(file.clone()),
-        Input::Text(..) => FileName::Stdin,
-    };
-
-    let krate = match parse_input(input, &parse_session, config) {
-        Ok(krate) => krate,
-        Err(err) => {
-            match err {
-                ParseError::Error(mut diagnostic) => diagnostic.emit(),
-                ParseError::Panic => {
-                    // Note that if you see this message and want more information,
-                    // then go to `parse_input` and run the parse function without
-                    // `catch_unwind` so rustfmt panics and you can get a backtrace.
-                    should_emit_verbose(&main_file, config, || {
-                        println!("The Rust parser panicked")
-                    });
-                }
-                ParseError::Recovered => {}
-            }
-            summary.add_parsing_error();
-            return Err((ErrorKind::ParseError, summary));
-        }
-    };
-
-    summary.mark_parse_time();
-
-    // Suppress error output after parsing.
-    let silent_emitter = Box::new(EmitterWriter::new(
-        Box::new(Vec::new()),
-        Some(codemap.clone()),
-        false,
-        false,
-    ));
-    parse_session.span_diagnostic = Handler::with_emitter(true, false, silent_emitter);
-
-    let report = FormatReport::new();
-
-    let format_result = format_ast(
-        &krate,
-        &mut parse_session,
-        &main_file,
-        config,
-        report.clone(),
-        |file_name, file, skipped_range, report| {
-            // For some reason, the codemap does not include terminating
-            // newlines so we must add one on for each file. This is sad.
-            filemap::append_newline(file);
-
-            format_lines(file, file_name, skipped_range, config, report);
-            replace_with_system_newlines(file, config);
-
-            if let Some(ref mut out) = out {
-                return filemap::write_file(file, file_name, out, config);
-            }
-            Ok(false)
-        },
-    );
-
-    summary.mark_format_time();
-
-    should_emit_verbose(&main_file, config, || {
-        fn duration_to_f32(d: Duration) -> f32 {
-            d.as_secs() as f32 + d.subsec_nanos() as f32 / 1_000_000_000f32
-        }
-
-        println!(
-            "Spent {0:.3} secs in the parsing phase, and {1:.3} secs in the formatting phase",
-            duration_to_f32(summary.get_parse_time().unwrap()),
-            duration_to_f32(summary.get_format_time().unwrap()),
-        )
-    });
-
-    {
-        let report_errs = &report.internal.borrow().1;
-        if report_errs.has_check_errors {
-            summary.add_check_error();
-        }
-        if report_errs.has_operational_errors {
-            summary.add_operational_error();
-        }
-    }
-
-    match format_result {
-        Ok((file_map, has_diff, has_macro_rewrite_failure)) => {
-            if report.has_warnings() {
-                summary.add_formatting_error();
-            }
-
-            if has_diff {
-                summary.add_diff();
-            }
-
-            if has_macro_rewrite_failure {
-                summary.add_macro_foramt_failure();
-            }
-
-            Ok((summary, file_map, report))
-        }
-        Err(e) => Err((From::from(e), summary)),
-    }
-}
-
-fn replace_with_system_newlines(text: &mut String, config: &Config) -> () {
-    let style = if config.newline_style() == NewlineStyle::Native {
-        if cfg!(windows) {
-            NewlineStyle::Windows
-        } else {
-            NewlineStyle::Unix
-        }
-    } else {
-        config.newline_style()
-    };
-
-    match style {
-        NewlineStyle::Unix => return,
-        NewlineStyle::Windows => {
-            let mut transformed = String::with_capacity(text.capacity());
-            for c in text.chars() {
-                match c {
-                    '\n' => transformed.push_str("\r\n"),
-                    '\r' => continue,
-                    c => transformed.push(c),
-                }
-            }
-            *text = transformed;
-        }
-        NewlineStyle::Native => unreachable!(),
-    }
-}
-
-/// A single span of changed lines, with 0 or more removed lines
-/// and a vector of 0 or more inserted lines.
-#[derive(Debug, PartialEq, Eq)]
-struct ModifiedChunk {
-    /// The first to be removed from the original text
-    pub line_number_orig: u32,
-    /// The number of lines which have been replaced
-    pub lines_removed: u32,
-    /// The new lines
-    pub lines: Vec<String>,
-}
-
-/// Set of changed sections of a file.
-#[derive(Debug, PartialEq, Eq)]
-struct ModifiedLines {
-    /// The set of changed chunks.
-    pub chunks: Vec<ModifiedChunk>,
-}
-
-/// Format a file and return a `ModifiedLines` data structure describing
-/// the changed ranges of lines.
-#[cfg(test)]
-fn get_modified_lines(
-    input: Input,
-    config: &Config,
-) -> Result<ModifiedLines, (ErrorKind, Summary)> {
-    use std::io::BufRead;
-
-    let mut data = Vec::new();
-
-    let mut config = config.clone();
-    config.set().emit_mode(config::EmitMode::ModifiedLines);
-    format_input(input, &config, Some(&mut data))?;
-
-    let mut lines = data.lines();
-    let mut chunks = Vec::new();
-    while let Some(Ok(header)) = lines.next() {
-        // Parse the header line
-        let values: Vec<_> = header
-            .split(' ')
-            .map(|s| s.parse::<u32>().unwrap())
-            .collect();
-        assert_eq!(values.len(), 3);
-        let line_number_orig = values[0];
-        let lines_removed = values[1];
-        let num_added = values[2];
-        let mut added_lines = Vec::new();
-        for _ in 0..num_added {
-            added_lines.push(lines.next().unwrap().unwrap());
-        }
-        chunks.push(ModifiedChunk {
-            line_number_orig,
-            lines_removed,
-            lines: added_lines,
-        });
-    }
-    Ok(ModifiedLines { chunks })
-}
-
 #[cfg(test)]
 mod unit_tests {
-    use super::{format_code_block, format_snippet, Config};
+    use super::*;
 
     #[test]
     fn test_no_panic_on_format_snippet_and_format_code_block() {

src/test/mod.rs

@@ -15,15 +15,17 @@ use syntax;
 use std::collections::{HashMap, HashSet};
 use std::env;
 use std::fs;
-use std::io::{self, BufRead, BufReader, Read};
+use std::io::{self, BufRead, BufReader, Read, Write};
 use std::iter::{Enumerate, Peekable};
 use std::path::{Path, PathBuf};
 use std::str::Chars;
 
 use config::summary::Summary;
-use config::{Color, Config, ReportTactic};
-use rustfmt_diff::*;
-use *;
+use config::{Color, Config, EmitMode, FileName, ReportTactic};
+use filemap;
+use formatting::{format_input_inner, get_modified_lines, FileMap, ModifiedChunk, ModifiedLines};
+use rustfmt_diff::{make_diff, print_diff, DiffLine, Mismatch, OutputWriter};
+use {format_input, FormatReport, Input};
 
 const DIFF_CONTEXT_SIZE: usize = 3;
 const CONFIGURATIONS_FILE_NAME: &str = "Configurations.md";