Barrett Ruth
b7477e3af2
Problem: the character-level blend intensity was hardcoded to 0.6, giving users no way to tune how strongly changed characters stand out from the line-level background. Solution: add highlights.blend_alpha config option (number, 0-1, default 0.6) with type validation and range check.
493 lines
22 KiB
Text
493 lines
22 KiB
Text
*diffs.nvim.txt* Syntax highlighting for diffs in Neovim
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Author: Barrett Ruth <br.barrettruth@gmail.com>
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License: MIT
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==============================================================================
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INTRODUCTION *diffs.nvim*
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diffs.nvim adds syntax highlighting to diff views. It overlays language-aware
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highlights on top of default diff highlighting in vim-fugitive and Neovim's
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built-in diff mode.
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Features: ~
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- Syntax highlighting in |:Git| summary diffs and commit detail views
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- Diff header highlighting (`diff --git`, `index`, `---`, `+++`)
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- Syntax highlighting in |:Gdiffsplit| / |:Gvdiffsplit| side-by-side diffs
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- |:Gdiff| command for unified diff against any git revision
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- Background-only diff colors for any `&diff` buffer (vimdiff, diffthis, etc.)
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- Vim syntax fallback for languages without a treesitter parser
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- Blended diff background colors that preserve syntax visibility
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- Optional diff prefix (`+`/`-`/` `) concealment
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- Gutter (line number) highlighting
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==============================================================================
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REQUIREMENTS *diffs-requirements*
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- Neovim 0.9.0+
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- vim-fugitive (https://github.com/tpope/vim-fugitive) (optional, for unified
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diff syntax highlighting in |:Git| and commit views)
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- Treesitter parsers for languages you want highlighted
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Note: The diff mode feature (background-only colors for |:diffthis|, vimdiff,
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etc.) works without vim-fugitive.
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==============================================================================
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SETUP *diffs-setup*
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Using lazy.nvim: >lua
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{
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'barrettruth/diffs.nvim',
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dependencies = { 'tpope/vim-fugitive' },
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}
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<
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The plugin works automatically with no configuration required. For
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customization, see |diffs-config|.
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==============================================================================
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CONFIGURATION *diffs-config*
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Configuration is done via `vim.g.diffs`. Set this before the plugin loads:
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>lua
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vim.g.diffs = {
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debug = false,
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debounce_ms = 0,
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hide_prefix = false,
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highlights = {
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background = true,
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gutter = true,
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blend_alpha = 0.6,
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context = {
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enabled = true,
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lines = 25,
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},
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treesitter = {
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enabled = true,
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max_lines = 500,
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},
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vim = {
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enabled = false,
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max_lines = 200,
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},
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intra = {
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enabled = true,
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algorithm = 'default',
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max_lines = 500,
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},
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},
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fugitive = {
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horizontal = 'du',
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vertical = 'dU',
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},
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}
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<
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*diffs.Config*
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Fields: ~
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{debug} (boolean, default: false)
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Enable debug logging to |:messages| with
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`[diffs]` prefix.
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{debounce_ms} (integer, default: 0)
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Debounce delay in milliseconds for re-highlighting
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after buffer changes. Lower values feel snappier
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but use more CPU.
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{hide_prefix} (boolean, default: false)
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Hide diff prefixes (`+`/`-`/` `) using virtual
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text overlay. Makes code appear without the
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leading diff character. When `highlights.background`
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is also enabled, the overlay inherits the line's
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background color.
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{highlights} (table, default: see below)
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Controls which highlight features are enabled.
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See |diffs.Highlights| for fields.
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{fugitive} (table, default: see below)
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Fugitive status buffer keymap options.
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See |diffs.FugitiveConfig| for fields.
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*diffs.Highlights*
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Highlights table fields: ~
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{background} (boolean, default: true)
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Apply background highlighting to `+`/`-` lines
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using `DiffsAdd`/`DiffsDelete` groups (derived
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from `DiffAdd`/`DiffDelete` backgrounds).
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{gutter} (boolean, default: true)
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Highlight line numbers with matching colors.
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Only visible if line numbers are enabled.
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{blend_alpha} (number, default: 0.6)
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Alpha value for character-level blend intensity.
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Controls how strongly changed characters stand
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out from the line-level background. Must be
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between 0 and 1 (inclusive). Higher values
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produce more vivid character-level highlights.
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{context} (table, default: see below)
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Syntax parsing context options.
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See |diffs.ContextConfig| for fields.
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{treesitter} (table, default: see below)
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Treesitter highlighting options.
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See |diffs.TreesitterConfig| for fields.
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{vim} (table, default: see below)
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Vim syntax highlighting options (experimental).
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See |diffs.VimConfig| for fields.
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{intra} (table, default: see below)
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Character-level (intra-line) diff highlighting.
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See |diffs.IntraConfig| for fields.
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*diffs.ContextConfig*
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Context config fields: ~
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{enabled} (boolean, default: true)
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Read lines from disk before and after each hunk
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to provide surrounding syntax context. Improves
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accuracy at hunk boundaries where incomplete
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constructs (e.g., a function definition with no
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body) would otherwise confuse the parser.
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{lines} (integer, default: 25)
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Number of context lines to read in each
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direction. Lines are read with early exit —
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cost scales with this value, not file size.
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*diffs.TreesitterConfig*
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Treesitter config fields: ~
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{enabled} (boolean, default: true)
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Apply treesitter syntax highlighting to code.
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{max_lines} (integer, default: 500)
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Skip treesitter highlighting for hunks larger than
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this many lines. Prevents lag on massive diffs.
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*diffs.VimConfig*
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Vim config fields: ~
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{enabled} (boolean, default: false)
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Use vim syntax highlighting as fallback when no
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treesitter parser is available for a language.
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Creates a scratch buffer, sets the filetype, and
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queries |synID()| per character to extract
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highlight groups. Slower than treesitter but
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covers languages without a TS parser installed.
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{max_lines} (integer, default: 200)
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Skip vim syntax highlighting for hunks larger than
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this many lines. Lower than the treesitter default
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due to the per-character cost of |synID()|.
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*diffs.IntraConfig*
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Intra config fields: ~
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{enabled} (boolean, default: true)
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Enable character-level diff highlighting within
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changed lines. When a line changes from `local x = 1`
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to `local x = 2`, only the `1`/`2` characters get
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an intense background overlay while the rest of the
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line keeps the softer line-level background.
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{algorithm} (string, default: 'default')
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Diff algorithm for character-level analysis.
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`'default'`: use |vim.diff()| with settings
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inherited from |'diffopt'| (`algorithm` and
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`linematch`). `'vscode'`: use libvscodediff FFI
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(falls back to default if not available).
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{max_lines} (integer, default: 500)
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Skip character-level highlighting for hunks larger
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than this many lines.
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Note: Header context (e.g., `@@ -10,3 +10,4 @@ func()`) is always
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highlighted with treesitter when a parser is available.
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Language detection uses Neovim's built-in |vim.filetype.match()| and
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|vim.treesitter.language.get_lang()|. To customize filetype detection
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or register treesitter parsers for custom filetypes, use
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|vim.filetype.add()| and |vim.treesitter.language.register()|.
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==============================================================================
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COMMANDS *diffs-commands*
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:Gdiff [revision] *:Gdiff*
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Open a unified diff of the current file against a git revision. Displays
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in a horizontal split below the current window.
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The diff buffer shows `+`/`-` lines with full syntax highlighting for the
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code language, plus diff header highlighting for `diff --git`, `---`,
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`+++`, and `@@` lines.
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Parameters: ~
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{revision} (string, optional) Git revision to diff against.
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Defaults to HEAD.
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Examples: >vim
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:Gdiff " diff against HEAD
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:Gdiff main " diff against main branch
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:Gdiff HEAD~3 " diff against 3 commits ago
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:Gdiff abc123 " diff against specific commit
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<
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:Gvdiff [revision] *:Gvdiff*
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Like |:Gdiff| but opens in a vertical split.
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:Ghdiff [revision] *:Ghdiff*
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Like |:Gdiff| but explicitly opens in a horizontal split.
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==============================================================================
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MAPPINGS *diffs-mappings*
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*<Plug>(diffs-gdiff)*
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<Plug>(diffs-gdiff) Show unified diff against HEAD in a horizontal
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split. Equivalent to |:Gdiff| with no arguments.
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*<Plug>(diffs-gvdiff)*
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<Plug>(diffs-gvdiff) Show unified diff against HEAD in a vertical
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split. Equivalent to |:Gvdiff| with no arguments.
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Example configuration: >lua
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vim.keymap.set('n', '<leader>gd', '<Plug>(diffs-gdiff)')
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vim.keymap.set('n', '<leader>gD', '<Plug>(diffs-gvdiff)')
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<
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==============================================================================
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FUGITIVE STATUS KEYMAPS *diffs-fugitive*
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When inside a vim-fugitive |:Git| status buffer, diffs.nvim provides keymaps
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to open unified diffs for files or entire sections.
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Keymaps: ~
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*diffs-du* *diffs-dU*
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du Open unified diff in a horizontal split.
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dU Open unified diff in a vertical split.
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These keymaps work on:
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- File lines (e.g., `M src/foo.lua`) - opens diff for that file
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- Section headers (e.g., `Staged (3)`) - opens diff for all files in section
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- Hunk/context lines below a file - opens diff for the parent file
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Behavior by file status: ~
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Status Section Base Current Result ~
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M Unstaged index working tree unstaged changes
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M Staged HEAD index staged changes
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A Staged (empty) index file as all-added
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D Staged HEAD (empty) file as all-removed
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R Staged HEAD:oldname index:newname content diff
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? Untracked (empty) working tree file as all-added
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On section headers, the keymap runs `git diff` (or `git diff --cached` for
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staged) and displays all changes in that section as a single unified diff.
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Untracked section headers show a warning since there is no meaningful diff.
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Configuration: ~
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*diffs.FugitiveConfig*
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>lua
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vim.g.diffs = {
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fugitive = {
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horizontal = 'du', -- keymap for horizontal split, false to disable
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vertical = 'dU', -- keymap for vertical split, false to disable
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},
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}
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<
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Fields: ~
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{horizontal} (string|false, default: 'du')
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Keymap for unified diff in horizontal split.
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Set to `false` to disable.
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{vertical} (string|false, default: 'dU')
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Keymap for unified diff in vertical split.
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Set to `false` to disable.
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==============================================================================
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API *diffs-api*
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attach({bufnr}) *diffs.attach()*
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Manually attach highlighting to a buffer. Called automatically for
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fugitive buffers via the `FileType fugitive` autocmd.
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Parameters: ~
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{bufnr} (integer, optional) Buffer number. Defaults to current buffer.
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refresh({bufnr}) *diffs.refresh()*
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Manually refresh highlighting for a buffer. Useful after external changes
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or for debugging.
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Parameters: ~
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{bufnr} (integer, optional) Buffer number. Defaults to current buffer.
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==============================================================================
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IMPLEMENTATION *diffs-implementation*
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Summary / commit detail views: ~
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1. `FileType fugitive` or `FileType git` (for `fugitive://` buffers)
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triggers |diffs.attach()|
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2. The buffer is parsed to detect file headers (`M path/to/file`,
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`diff --git a/... b/...`) and hunk headers (`@@ -10,3 +10,4 @@`)
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3. For each hunk:
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- Language is detected from the filename using |vim.filetype.match()|
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- Diff prefixes (`+`/`-`/` `) are stripped from code lines
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- Code is parsed with |vim.treesitter.get_string_parser()|
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- If no treesitter parser and `vim.enabled`: vim syntax fallback via
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scratch buffer and |synID()|
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- `Normal` extmarks at priority 198 clear underlying diff foreground
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- Background extmarks (`DiffsAdd`/`DiffsDelete`) at priority 199
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- Syntax highlights are applied as extmarks at priority 200
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- Character-level diff extmarks (`DiffsAddText`/`DiffsDeleteText`) at
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priority 201 overlay changed characters with an intense background
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- Conceal extmarks hide diff prefixes when `hide_prefix` is enabled
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4. Re-highlighting occurs on `TextChanged` (debounced) and `Syntax` events
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Diff mode views: ~
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1. `OptionSet diff` detects when any window enters diff mode
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2. All `&diff` windows in the tabpage receive a window-local 'winhighlight'
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override that remaps `DiffAdd`/`DiffDelete`/`DiffChange`/`DiffText` to
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background-only variants, allowing existing treesitter highlighting to
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show through the diff colors
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==============================================================================
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KNOWN LIMITATIONS *diffs-limitations*
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Incomplete Syntax Context ~
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*diffs-syntax-context*
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Treesitter parses each diff hunk in isolation. To provide surrounding code
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context, diffs.nvim reads lines from disk before and after each hunk
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(see |diffs.ContextConfig|, enabled by default). This resolves most boundary
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issues where incomplete constructs (e.g., a function definition at the edge
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of a hunk with no body) would confuse the parser.
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Set `highlights.context.enabled = false` to disable context padding. In rare
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cases, context padding may not help if the relevant surrounding code is very
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far from the hunk boundaries.
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Syntax Highlighting Flash ~
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*diffs-flash*
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When opening a fugitive buffer, there is an unavoidable visual "flash" where
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the buffer briefly shows fugitive's default diff highlighting before
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diffs.nvim applies treesitter highlights.
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This occurs because diffs.nvim hooks into the `FileType fugitive` event,
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which fires after vim-fugitive has already painted the buffer. Even with
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`debounce_ms = 0`, the re-painting goes through Neovim's event loop.
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To minimize the flash, use a low debounce value: >lua
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vim.g.diffs = {
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debounce_ms = 0,
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}
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<
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Conflicting Diff Plugins ~
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*diffs-plugin-conflicts*
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diffs.nvim may not interact well with other plugins that modify diff
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highlighting or the sign column in diff views. Known plugins that may
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conflict:
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- diffview.nvim (sindrets/diffview.nvim)
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Provides its own diff highlighting and conflict resolution UI.
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When using diffview.nvim for viewing diffs, you may want to disable
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diffs.nvim's diff mode attachment or use one plugin exclusively.
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- mini.diff (echasnovski/mini.diff)
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Visualizes buffer differences with its own highlighting system.
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May override or conflict with diffs.nvim's background highlighting.
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- gitsigns.nvim (lewis6991/gitsigns.nvim)
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Generally compatible for sign column decorations, but both plugins
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modifying line highlights may produce unexpected results.
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- git-conflict.nvim (akinsho/git-conflict.nvim)
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Provides conflict marker highlighting that may overlap with
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diffs.nvim's highlighting in conflict scenarios.
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If you experience visual conflicts, try disabling the conflicting plugin's
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diff-related features.
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==============================================================================
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HIGHLIGHT GROUPS *diffs-highlights*
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diffs.nvim defines custom highlight groups. All groups use `default = true`,
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so colorschemes can override them by defining the group before the plugin
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loads.
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All derived groups are computed by alpha-blending a source color into the
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`Normal` background. Line-level groups blend at 40% alpha for a subtle tint;
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character-level groups blend at 60% for more contrast. Line-number groups
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combine both: background from the line-level blend, foreground from the
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character-level blend.
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Fugitive unified diff highlights: ~
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*DiffsAdd*
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DiffsAdd Background for `+` lines. Derived by blending
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`DiffAdd` background with `Normal` at 40% alpha.
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*DiffsDelete*
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DiffsDelete Background for `-` lines. Derived by blending
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`DiffDelete` background with `Normal` at 40% alpha.
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*DiffsAddNr*
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DiffsAddNr Line number for `+` lines. Foreground from
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`DiffsAddText`, background from `DiffsAdd`.
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*DiffsDeleteNr*
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DiffsDeleteNr Line number for `-` lines. Foreground from
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`DiffsDeleteText`, background from `DiffsDelete`.
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*DiffsAddText*
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DiffsAddText Character-level background for changed characters
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within `+` lines. Derived by blending `diffAdded`
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foreground with `Normal` background at 60% alpha.
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Only sets `bg`, so treesitter foreground colors show
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through.
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*DiffsDeleteText*
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DiffsDeleteText Character-level background for changed characters
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within `-` lines. Derived by blending `diffRemoved`
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foreground with `Normal` background at 60% alpha.
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Diff mode window highlights: ~
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These are used for |winhighlight| remapping in `&diff` windows.
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*DiffsDiffAdd*
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DiffsDiffAdd Background-only. Derived from `DiffAdd` bg.
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Treesitter provides foreground syntax highlighting.
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*DiffsDiffDelete*
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DiffsDiffDelete Foreground and background from `DiffDelete`.
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Used for filler lines (`/////`) which have no real
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code content to highlight.
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*DiffsDiffChange*
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DiffsDiffChange Background-only. Derived from `DiffChange` bg.
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Treesitter provides foreground syntax highlighting.
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*DiffsDiffText*
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DiffsDiffText Background-only. Derived from `DiffText` bg.
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Treesitter provides foreground syntax highlighting.
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To customize these in your colorscheme: >lua
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vim.api.nvim_set_hl(0, 'DiffsAdd', { bg = '#2e4a3a' })
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vim.api.nvim_set_hl(0, 'DiffsDiffDelete', { link = 'DiffDelete' })
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<
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==============================================================================
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HEALTH CHECK *diffs-health*
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Run |:checkhealth| diffs to verify your setup.
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Checks performed:
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- Neovim version >= 0.9.0
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- vim-fugitive is installed (optional)
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- libvscode_diff shared library is available (optional)
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==============================================================================
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ACKNOWLEDGEMENTS *diffs-acknowledgements*
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- vim-fugitive (https://github.com/tpope/vim-fugitive)
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- codediff.nvim (https://github.com/esmuellert/codediff.nvim)
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- diffview.nvim (https://github.com/sindrets/diffview.nvim)
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- @phanen (https://github.com/phanen) - diff header highlighting,
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treesitter injection support
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==============================================================================
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vim:tw=78:ts=8:ft=help:norl:
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