diffs.nvim/lua/diffs/highlight.lua
Barrett Ruth 3482e25c41 fix(highlight): use hl_group instead of line_hl_group for diff backgrounds
line_hl_group bg occupies a separate rendering channel from hl_group in
Neovim's extmark system, causing character-level bg-only highlights to be
invisible regardless of priority. Switching to hl_group + hl_eol ensures
all backgrounds compete in the same channel.

Also reorders priorities (Normal 198 < line bg 199 < syntax 200 < char
bg 201), bumps char-level blend alpha from 0.4 to 0.7 for visibility,
and adds debug logging throughout the intra pipeline.
2026-02-06 18:28:22 -05:00

383 lines
11 KiB
Lua

local M = {}
local dbg = require('diffs.log').dbg
local diff = require('diffs.diff')
---@param bufnr integer
---@param ns integer
---@param hunk diffs.Hunk
---@param col_offset integer
---@param text string
---@param lang string
---@return integer
local function highlight_text(bufnr, ns, hunk, col_offset, text, lang)
local ok, parser_obj = pcall(vim.treesitter.get_string_parser, text, lang)
if not ok or not parser_obj then
return 0
end
local trees = parser_obj:parse()
if not trees or #trees == 0 then
return 0
end
local query = vim.treesitter.query.get(lang, 'highlights')
if not query then
return 0
end
local extmark_count = 0
local header_line = hunk.start_line - 1
for id, node, metadata in query:iter_captures(trees[1]:root(), text) do
local capture_name = '@' .. query.captures[id] .. '.' .. lang
local sr, sc, er, ec = node:range()
local buf_sr = header_line + sr
local buf_er = header_line + er
local buf_sc = col_offset + sc
local buf_ec = col_offset + ec
local priority = lang == 'diff' and (tonumber(metadata.priority) or 100) or 200
pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_sr, buf_sc, {
end_row = buf_er,
end_col = buf_ec,
hl_group = capture_name,
priority = priority,
})
extmark_count = extmark_count + 1
end
return extmark_count
end
---@class diffs.HunkOpts
---@field hide_prefix boolean
---@field highlights diffs.Highlights
---@param bufnr integer
---@param ns integer
---@param hunk diffs.Hunk
---@param code_lines string[]
---@param col_offset integer?
---@return integer
local function highlight_treesitter(bufnr, ns, hunk, code_lines, col_offset)
local lang = hunk.lang
if not lang then
return 0
end
local code = table.concat(code_lines, '\n')
if code == '' then
return 0
end
local ok, parser_obj = pcall(vim.treesitter.get_string_parser, code, lang)
if not ok or not parser_obj then
dbg('failed to create parser for lang: %s', lang)
return 0
end
local trees = parser_obj:parse()
if not trees or #trees == 0 then
dbg('parse returned no trees for lang: %s', lang)
return 0
end
local query = vim.treesitter.query.get(lang, 'highlights')
if not query then
dbg('no highlights query for lang: %s', lang)
return 0
end
if hunk.header_context and hunk.header_context_col then
local header_line = hunk.start_line - 1
pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, header_line, hunk.header_context_col, {
end_col = hunk.header_context_col + #hunk.header_context,
hl_group = 'Normal',
priority = 199,
})
local header_extmarks =
highlight_text(bufnr, ns, hunk, hunk.header_context_col, hunk.header_context, lang)
if header_extmarks > 0 then
dbg('header %s:%d applied %d extmarks', hunk.filename, hunk.start_line, header_extmarks)
end
end
col_offset = col_offset or 1
local extmark_count = 0
for id, node, metadata in query:iter_captures(trees[1]:root(), code) do
local capture_name = '@' .. query.captures[id] .. '.' .. lang
local sr, sc, er, ec = node:range()
local buf_sr = hunk.start_line + sr
local buf_er = hunk.start_line + er
local buf_sc = sc + col_offset
local buf_ec = ec + col_offset
local priority = lang == 'diff' and (tonumber(metadata.priority) or 100) or 200
pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_sr, buf_sc, {
end_row = buf_er,
end_col = buf_ec,
hl_group = capture_name,
priority = priority,
})
extmark_count = extmark_count + 1
end
return extmark_count
end
---@alias diffs.SyntaxQueryFn fun(line: integer, col: integer): integer, string
---@param query_fn diffs.SyntaxQueryFn
---@param code_lines string[]
---@return {line: integer, col_start: integer, col_end: integer, hl_name: string}[]
function M.coalesce_syntax_spans(query_fn, code_lines)
local spans = {}
for i, line in ipairs(code_lines) do
local col = 1
local line_len = #line
while col <= line_len do
local syn_id, hl_name = query_fn(i, col)
if syn_id == 0 then
col = col + 1
else
local span_start = col
col = col + 1
while col <= line_len do
local next_id, next_name = query_fn(i, col)
if next_id == 0 or next_name ~= hl_name then
break
end
col = col + 1
end
if hl_name ~= '' then
table.insert(spans, {
line = i,
col_start = span_start,
col_end = col,
hl_name = hl_name,
})
end
end
end
end
return spans
end
---@param bufnr integer
---@param ns integer
---@param hunk diffs.Hunk
---@param code_lines string[]
---@return integer
local function highlight_vim_syntax(bufnr, ns, hunk, code_lines)
local ft = hunk.ft
if not ft then
return 0
end
if #code_lines == 0 then
return 0
end
local scratch = vim.api.nvim_create_buf(false, true)
vim.api.nvim_buf_set_lines(scratch, 0, -1, false, code_lines)
vim.api.nvim_set_option_value('bufhidden', 'wipe', { buf = scratch })
local spans = {}
vim.api.nvim_buf_call(scratch, function()
vim.cmd('setlocal syntax=' .. ft)
vim.cmd('redraw')
---@param line integer
---@param col integer
---@return integer, string
local function query_fn(line, col)
local syn_id = vim.fn.synID(line, col, 1)
if syn_id == 0 then
return 0, ''
end
return syn_id, vim.fn.synIDattr(vim.fn.synIDtrans(syn_id), 'name')
end
spans = M.coalesce_syntax_spans(query_fn, code_lines)
end)
vim.api.nvim_buf_delete(scratch, { force = true })
local extmark_count = 0
for _, span in ipairs(spans) do
local buf_line = hunk.start_line + span.line - 1
pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, span.col_start, {
end_col = span.col_end,
hl_group = span.hl_name,
priority = 200,
})
extmark_count = extmark_count + 1
end
return extmark_count
end
---@param bufnr integer
---@param ns integer
---@param hunk diffs.Hunk
---@param opts diffs.HunkOpts
function M.highlight_hunk(bufnr, ns, hunk, opts)
local use_ts = hunk.lang and opts.highlights.treesitter.enabled
local use_vim = not use_ts and hunk.ft and opts.highlights.vim.enabled
local max_lines = use_ts and opts.highlights.treesitter.max_lines or opts.highlights.vim.max_lines
if (use_ts or use_vim) and #hunk.lines > max_lines then
dbg(
'skipping hunk %s:%d (%d lines > %d max)',
hunk.filename,
hunk.start_line,
#hunk.lines,
max_lines
)
use_ts = false
use_vim = false
end
local apply_syntax = use_ts or use_vim
---@type string[]
local code_lines = {}
if apply_syntax then
for _, line in ipairs(hunk.lines) do
table.insert(code_lines, line:sub(2))
end
end
local extmark_count = 0
if use_ts then
extmark_count = highlight_treesitter(bufnr, ns, hunk, code_lines)
elseif use_vim then
extmark_count = highlight_vim_syntax(bufnr, ns, hunk, code_lines)
end
if
hunk.header_start_line
and hunk.header_lines
and #hunk.header_lines > 0
and opts.highlights.treesitter.enabled
then
extmark_count = extmark_count
+ highlight_treesitter(bufnr, ns, {
filename = hunk.filename,
start_line = hunk.header_start_line - 1,
lang = 'diff',
lines = hunk.header_lines,
header_lines = {},
}, hunk.header_lines, 0)
end
local syntax_applied = extmark_count > 0
---@type diffs.IntraChanges?
local intra = nil
local intra_cfg = opts.highlights.intra
if intra_cfg and intra_cfg.enabled and #hunk.lines <= intra_cfg.max_lines then
dbg('computing intra for hunk %s:%d (%d lines)', hunk.filename, hunk.start_line, #hunk.lines)
intra = diff.compute_intra_hunks(hunk.lines, intra_cfg.algorithm)
if intra then
dbg('intra result: %d add spans, %d del spans', #intra.add_spans, #intra.del_spans)
else
dbg('intra result: nil (no change groups)')
end
elseif intra_cfg and not intra_cfg.enabled then
dbg('intra disabled by config')
elseif intra_cfg and #hunk.lines > intra_cfg.max_lines then
dbg('intra skipped: %d lines > %d max', #hunk.lines, intra_cfg.max_lines)
end
---@type table<integer, diffs.CharSpan[]>
local char_spans_by_line = {}
if intra then
for _, span in ipairs(intra.add_spans) do
if not char_spans_by_line[span.line] then
char_spans_by_line[span.line] = {}
end
table.insert(char_spans_by_line[span.line], span)
end
for _, span in ipairs(intra.del_spans) do
if not char_spans_by_line[span.line] then
char_spans_by_line[span.line] = {}
end
table.insert(char_spans_by_line[span.line], span)
end
end
for i, line in ipairs(hunk.lines) do
local buf_line = hunk.start_line + i - 1
local line_len = #line
local prefix = line:sub(1, 1)
local is_diff_line = prefix == '+' or prefix == '-'
local line_hl = is_diff_line and (prefix == '+' and 'DiffsAdd' or 'DiffsDelete') or nil
local number_hl = is_diff_line and (prefix == '+' and 'DiffsAddNr' or 'DiffsDeleteNr') or nil
if opts.hide_prefix then
local virt_hl = (opts.highlights.background and line_hl) or nil
pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 0, {
virt_text = { { ' ', virt_hl } },
virt_text_pos = 'overlay',
})
end
if line_len > 1 and syntax_applied then
pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 1, {
end_col = line_len,
hl_group = 'Normal',
priority = 198,
})
end
if opts.highlights.background and is_diff_line then
pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 0, {
end_col = line_len,
hl_group = line_hl,
hl_eol = true,
number_hl_group = opts.highlights.gutter and number_hl or nil,
priority = 199,
})
end
if char_spans_by_line[i] then
local char_hl = prefix == '+' and 'DiffsAddText' or 'DiffsDeleteText'
for _, span in ipairs(char_spans_by_line[i]) do
dbg(
'char extmark: line=%d buf_line=%d col=%d..%d hl=%s text="%s"',
i,
buf_line,
span.col_start,
span.col_end,
char_hl,
line:sub(span.col_start + 1, span.col_end)
)
local ok, err = pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, span.col_start, {
end_col = span.col_end,
hl_group = char_hl,
priority = 201,
})
if not ok then
dbg('char extmark FAILED: %s', err)
end
extmark_count = extmark_count + 1
end
end
end
dbg('hunk %s:%d applied %d extmarks', hunk.filename, hunk.start_line, extmark_count)
end
return M