Display merge conflicts

Author: dandavison

README.md

@@ -27,6 +27,9 @@
 [delta]
     navigate = true
 
+[merge]
+    conflictstyle = diff3
+
 [diff]
     colorMoved = default
 

etc/examples/822-hunk-header-within-merge-conflict.diff

@@ -435,6 +435,50 @@ pub struct Opt {
     /// (underline), 'ol' (overline), or the combination 'ul ol'.
     pub hunk_header_decoration_style: String,
 
+    #[structopt(long = "merge-conflict-begin-symbol", default_value = "▼")]
+    /// A string that is repeated to form the line marking the beginning of a merge conflict region.
+    pub merge_conflict_begin_symbol: String,
+
+    #[structopt(long = "merge-conflict-end-symbol", default_value = "▲")]
+    /// A string that is repeated to form the line marking the end of a merge conflict region.
+    pub merge_conflict_end_symbol: String,
+
+    #[structopt(
+        long = "merge-conflict-ours-diff-header-style",
+        default_value = "normal"
+    )]
+    /// Style (foreground, background, attributes) for the header above the diff between the
+    /// ancestral commit and 'our' branch. See STYLES section.
+    pub merge_conflict_ours_diff_header_style: String,
+
+    #[structopt(
+        long = "merge-conflict-ours-diff-header-decoration-style",
+        default_value = "box"
+    )]
+    /// Style (foreground, background, attributes) for the decoration of the header above the diff
+    /// between the ancestral commit and 'our' branch.  See STYLES section. The style string should
+    /// contain one of the special attributes 'box', 'ul' (underline), 'ol' (overline), or the
+    /// combination 'ul ol'.
+    pub merge_conflict_ours_diff_header_decoration_style: String,
+
+    #[structopt(
+        long = "merge-conflict-theirs-diff-header-style",
+        default_value = "normal"
+    )]
+    /// Style (foreground, background, attributes) for the header above the diff between the
+    /// ancestral commit and 'their' branch. See STYLES section.
+    pub merge_conflict_theirs_diff_header_style: String,
+
+    #[structopt(
+        long = "merge-conflict-theirs-diff-header-decoration-style",
+        default_value = "box"
+    )]
+    /// Style (foreground, background, attributes) for the decoration of the header above the diff
+    /// between the ancestral commit and 'their' branch.  See STYLES section. The style string should
+    /// contain one of the special attributes 'box', 'ul' (underline), 'ol' (overline), or the
+    /// combination 'ul ol'.
+    pub merge_conflict_theirs_diff_header_decoration_style: String,
+
     #[structopt(long = "map-styles")]
     /// A string specifying a mapping styles encountered in raw input to desired
     /// output styles. An example is

src/cli.rs

@@ -87,6 +87,7 @@ pub struct Config {
     pub grep_match_line_style: Style,
     pub grep_match_word_style: Style,
     pub grep_separator_symbol: String,
+    pub handle_merge_conflicts: bool,
     pub hunk_header_file_style: Style,
     pub hunk_header_line_number_style: Style,
     pub hunk_header_style_include_file_path: bool,
@@ -110,6 +111,10 @@ pub struct Config {
     pub max_line_distance_for_naively_paired_lines: f64,
     pub max_line_distance: f64,
     pub max_line_length: usize,
+    pub merge_conflict_begin_symbol: String,
+    pub merge_conflict_ours_diff_header_style: Style,
+    pub merge_conflict_theirs_diff_header_style: Style,
+    pub merge_conflict_end_symbol: String,
     pub minus_emph_style: Style,
     pub minus_empty_line_marker_style: Style,
     pub minus_file: Option<PathBuf>,
@@ -260,6 +265,7 @@ impl From<cli::Opt> for Config {
             grep_match_line_style: styles["grep-match-line-style"],
             grep_match_word_style: styles["grep-match-word-style"],
             grep_separator_symbol: opt.grep_separator_symbol,
+            handle_merge_conflicts: !opt.raw,
             hunk_header_file_style: styles["hunk-header-file-style"],
             hunk_header_line_number_style: styles["hunk-header-line-number-style"],
             hunk_header_style: styles["hunk-header-style"],
@@ -320,6 +326,11 @@ impl From<cli::Opt> for Config {
                     )
                 }
             },
+            merge_conflict_begin_symbol: opt.merge_conflict_begin_symbol,
+            merge_conflict_ours_diff_header_style: styles["merge-conflict-ours-diff-header-style"],
+            merge_conflict_theirs_diff_header_style: styles
+                ["merge-conflict-theirs-diff-header-style"],
+            merge_conflict_end_symbol: opt.merge_conflict_end_symbol,
             minus_emph_style: styles["minus-emph-style"],
             minus_empty_line_marker_style: styles["minus-empty-line-marker-style"],
             minus_file: opt.minus_file,

src/config.rs

@@ -6,25 +6,27 @@ use std::io::Write;
 use bytelines::ByteLines;
 
 use crate::ansi;
+use crate::config::delta_unreachable;
 use crate::config::Config;
 use crate::features;
-use crate::handlers;
+use crate::handlers::{self, merge_conflict};
 use crate::paint::Painter;
 use crate::style::DecorationStyle;
 
 #[derive(Clone, Debug, PartialEq)]
 pub enum State {
-    CommitMeta,                                // In commit metadata section
+    CommitMeta,                           // In commit metadata section
     DiffHeader(DiffType), // In diff metadata section, between (possible) commit metadata and first hunk
-    HunkHeader(DiffType, String, String), // In hunk metadata line (line, raw_line)
-    HunkZero(Option<String>), // In hunk; unchanged line (prefix)
-    HunkMinus(Option<String>, Option<String>), // In hunk; removed line (prefix, raw_line)
-    HunkPlus(Option<String>, Option<String>), // In hunk; added line (prefix, raw_line)
-    SubmoduleLog,         // In a submodule section, with gitconfig diff.submodule = log
+    HunkHeader(DiffType, String, String), // In hunk metadata line (diff_type, line, raw_line)
+    HunkZero(DiffType),   // In hunk; unchanged line (prefix)
+    HunkMinus(DiffType, Option<String>), // In hunk; removed line (diff_type, raw_line)
+    HunkPlus(DiffType, Option<String>), // In hunk; added line (diff_type, raw_line)
+    MergeConflict(MergeParents, merge_conflict::MergeConflictCommit),
+    SubmoduleLog, // In a submodule section, with gitconfig diff.submodule = log
     SubmoduleShort(String), // In a submodule section, with gitconfig diff.submodule = short
     Blame(String, Option<String>), // In a line of `git blame` output (commit, repeat_blame_line).
-    GitShowFile,          // In a line of `git show $revision:./path/to/file.ext` output
-    Grep,                 // In a line of `git grep` output
+    GitShowFile,  // In a line of `git show $revision:./path/to/file.ext` output
+    Grep,         // In a line of `git grep` output
     Unknown,
     // The following elements are created when a line is wrapped to display it:
     HunkZeroWrapped,  // Wrapped unchanged line
@@ -35,7 +37,27 @@ pub enum State {
 #[derive(Clone, Debug, PartialEq)]
 pub enum DiffType {
     Unified,
-    Combined(usize), // number of parent commits: https://git-scm.com/docs/git-diff#_combined_diff_format
+    Combined(MergeParents), // https://git-scm.com/docs/git-diff#_combined_diff_format
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub enum MergeParents {
+    Number(usize),  // Number of parent commits == (number of @s in hunk header) - 1
+    Prefix(String), // Hunk line prefix, length == number of parent commits
+    Unknown,
+}
+
+impl DiffType {
+    pub fn n_parents(&self) -> usize {
+        use DiffType::*;
+        use MergeParents::*;
+        match self {
+            Combined(Prefix(prefix)) => prefix.len(),
+            Combined(Number(n_parents)) => *n_parents,
+            Unified => 1,
+            Combined(Unknown) => delta_unreachable("Number of merge parents must be known."),
+        }
+    }
 }
 
 #[derive(Debug, PartialEq)]
@@ -131,6 +153,7 @@ impl<'a> StateMachine<'a> {
                 || self.handle_diff_header_misc_line()?
                 || self.handle_submodule_log_line()?
                 || self.handle_submodule_short_line()?
+                || self.handle_merge_conflict_line()?
                 || self.handle_hunk_line()?
                 || self.handle_git_show_file_line()?
                 || self.handle_blame_line()?

src/delta.rs

@@ -5,6 +5,7 @@ use unicode_segmentation::UnicodeSegmentation;
 use crate::ansi;
 use crate::cli;
 use crate::config::{self, delta_unreachable, Config};
+use crate::delta::DiffType;
 use crate::delta::State;
 use crate::edits;
 use crate::features::{line_numbers, OptionValueFunction};
@@ -180,7 +181,7 @@ pub fn paint_minus_and_plus_lines_side_by_side(
             &lines_have_homolog[Left],
             match minus_line_index {
                 Some(i) => &line_states[Left][i],
-                None => &State::HunkMinus(None, None),
+                None => &State::HunkMinus(DiffType::Unified, None),
             },
             &mut Some(line_numbers_data),
             bg_should_fill[Left],
@@ -201,7 +202,7 @@ pub fn paint_minus_and_plus_lines_side_by_side(
             &lines_have_homolog[Right],
             match plus_line_index {
                 Some(i) => &line_states[Right][i],
-                None => &State::HunkPlus(None, None),
+                None => &State::HunkPlus(DiffType::Unified, None),
             },
             &mut Some(line_numbers_data),
             bg_should_fill[Right],
@@ -222,7 +223,7 @@ pub fn paint_zero_lines_side_by_side<'a>(
     painted_prefix: Option<ansi_term::ANSIString>,
     background_color_extends_to_terminal_width: BgShouldFill,
 ) {
-    let states = vec![State::HunkZero(None)];
+    let states = vec![State::HunkZero(DiffType::Unified)];
 
     let (states, syntax_style_sections, diff_style_sections) = wrap_zero_block(
         config,
@@ -418,8 +419,12 @@ fn paint_minus_or_plus_panel_line<'a>(
             )
         } else {
             let opposite_state = match state {
-                State::HunkMinus(_, s) => State::HunkPlus(None, s.clone()),
-                State::HunkPlus(_, s) => State::HunkMinus(None, s.clone()),
+                State::HunkMinus(DiffType::Unified, s) => {
+                    State::HunkPlus(DiffType::Unified, s.clone())
+                }
+                State::HunkPlus(DiffType::Unified, s) => {
+                    State::HunkMinus(DiffType::Unified, s.clone())
+                }
                 _ => unreachable!(),
             };
             (

src/features/side_by_side.rs

@@ -1,4 +1,4 @@
-use crate::delta::{DiffType, State, StateMachine};
+use crate::delta::{DiffType, MergeParents, State, StateMachine};
 
 impl<'a> StateMachine<'a> {
     #[inline]
@@ -14,7 +14,8 @@ impl<'a> StateMachine<'a> {
         self.painter.paint_buffered_minus_and_plus_lines();
         self.state =
             if self.line.starts_with("diff --cc ") || self.line.starts_with("diff --combined ") {
-                State::DiffHeader(DiffType::Combined(2)) // We will confirm the number of parents when we see the hunk header
+                // We will determine the number of parents when we see the hunk header.
+                State::DiffHeader(DiffType::Combined(MergeParents::Unknown))
             } else {
                 State::DiffHeader(DiffType::Unified)
             };

src/handlers/diff_header_diff.rs

@@ -53,7 +53,7 @@ fn write_no_decoration(
 
 /// Write text to stream, surrounded by a box, leaving the cursor just
 /// beyond the bottom right corner.
-fn write_boxed(
+pub fn write_boxed(
     writer: &mut dyn Write,
     text: &str,
     raw_text: &str,