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feat(highlight): add treesitter context padding from disk

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Problem: treesitter parses each diff hunk in isolation, so incomplete
syntax constructs at hunk boundaries (e.g., a function definition with
no body) produce ERROR nodes and drop captures.

Solution: read N lines from the on-disk file before/after each hunk and
prepend/append them as unmapped padding lines. The line_map guard in
highlight_treesitter skips extmarks for unmapped lines, so padding
provides syntax context without visual output. Controlled by
highlights.context (default 25, 0 to disable). Also applies to the vim
syntax fallback path via a leading_offset filter.
This commit is contained in:
Barrett Ruth 2026-02-07 13:05:53 -05:00
parent ba1f830629
commit 2e1ebdee03
7 changed files with 308 additions and 24 deletions
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79
spec/parser_spec.lua
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@ -421,5 +421,84 @@ describe('parser', function()
os.remove(file_path)
vim.fn.delete(repo_root, 'rf')
end)
it('extracts file line numbers from @@ header', function()
local bufnr = create_buffer({
'M lua/test.lua',
'@@ -1,3 +1,4 @@',
' local M = {}',
'+local new = true',
' return M',
})
local hunks = parser.parse_buffer(bufnr)
assert.are.equal(1, #hunks)
assert.are.equal(1, hunks[1].file_old_start)
assert.are.equal(3, hunks[1].file_old_count)
assert.are.equal(1, hunks[1].file_new_start)
assert.are.equal(4, hunks[1].file_new_count)
delete_buffer(bufnr)
end)
it('extracts large line numbers from @@ header', function()
local bufnr = create_buffer({
'M lua/test.lua',
'@@ -100,20 +200,30 @@',
' local M = {}',
})
local hunks = parser.parse_buffer(bufnr)
assert.are.equal(1, #hunks)
assert.are.equal(100, hunks[1].file_old_start)
assert.are.equal(20, hunks[1].file_old_count)
assert.are.equal(200, hunks[1].file_new_start)
assert.are.equal(30, hunks[1].file_new_count)
delete_buffer(bufnr)
end)
it('defaults count to 1 when omitted in @@ header', function()
local bufnr = create_buffer({
'M lua/test.lua',
'@@ -1 +1 @@',
' local M = {}',
})
local hunks = parser.parse_buffer(bufnr)
assert.are.equal(1, #hunks)
assert.are.equal(1, hunks[1].file_old_start)
assert.are.equal(1, hunks[1].file_old_count)
assert.are.equal(1, hunks[1].file_new_start)
assert.are.equal(1, hunks[1].file_new_count)
delete_buffer(bufnr)
end)
it('stores repo_root on hunk when available', function()
local bufnr = create_buffer({
'M lua/test.lua',
'@@ -1,3 +1,4 @@',
' local M = {}',
'+local new = true',
' return M',
})
vim.api.nvim_buf_set_var(bufnr, 'diffs_repo_root', '/tmp/test-repo')
local hunks = parser.parse_buffer(bufnr)
assert.are.equal(1, #hunks)
assert.are.equal('/tmp/test-repo', hunks[1].repo_root)
delete_buffer(bufnr)
end)
it('repo_root is nil when not available', function()
local bufnr = create_buffer({
'M lua/test.lua',
'@@ -1,3 +1,4 @@',
' local M = {}',
})
local hunks = parser.parse_buffer(bufnr)
assert.are.equal(1, #hunks)
assert.is_nil(hunks[1].repo_root)
delete_buffer(bufnr)
end)
end)
end)