barrett/diffs.nvim
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions 13

feat(highlight): add treesitter context padding from disk

Browse source 
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
Download patch file Download diff file Expand all files Collapse all files

96
spec/highlight_spec.lua
View file

@ -37,6 +37,7 @@ describe('highlight', function()
highlights = {
background = false,
gutter = false,
context = 0,
treesitter = {
enabled = true,
max_lines = 500,
@ -1055,6 +1056,99 @@ describe('highlight', function()
assert.is_true(min_line_bg < min_char_bg)
delete_buffer(bufnr)
end)
it('context padding produces no extmarks on padding lines', function()
local repo_root = '/tmp/diffs-test-context'
vim.fn.mkdir(repo_root, 'p')
local f = io.open(repo_root .. '/test.lua', 'w')
f:write('local M = {}\n')
f:write('function M.hello()\n')
f:write(' return "hi"\n')
f:write('end\n')
f:write('return M\n')
f:close()
local bufnr = create_buffer({
'@@ -3,1 +3,2 @@',
' return "hi"',
'+"bye"',
})
local hunk = {
filename = 'test.lua',
lang = 'lua',
start_line = 1,
lines = { ' return "hi"', '+"bye"' },
file_old_start = 3,
file_old_count = 1,
file_new_start = 3,
file_new_count = 2,
repo_root = repo_root,
}
highlight.highlight_hunk(bufnr, ns, hunk, default_opts({ highlights = { context = 25 } }))
local extmarks = get_extmarks(bufnr)
for _, mark in ipairs(extmarks) do
local row = mark[2]
assert.is_true(row >= 1 and row <= 2)
end
delete_buffer(bufnr)
os.remove(repo_root .. '/test.lua')
vim.fn.delete(repo_root, 'rf')
end)
it('context = 0 matches behavior without padding', function()
local bufnr = create_buffer({
'@@ -1,1 +1,2 @@',
' local x = 1',
'+local y = 2',
})
local hunk = {
filename = 'test.lua',
lang = 'lua',
start_line = 1,
lines = { ' local x = 1', '+local y = 2' },
file_new_start = 1,
file_new_count = 2,
repo_root = '/nonexistent',
}
highlight.highlight_hunk(bufnr, ns, hunk, default_opts({ highlights = { context = 0 } }))
local extmarks = get_extmarks(bufnr)
assert.is_true(#extmarks > 0)
delete_buffer(bufnr)
end)
it('gracefully handles missing file for context padding', function()
local bufnr = create_buffer({
'@@ -1,1 +1,2 @@',
' local x = 1',
'+local y = 2',
})
local hunk = {
filename = 'test.lua',
lang = 'lua',
start_line = 1,
lines = { ' local x = 1', '+local y = 2' },
file_new_start = 1,
file_new_count = 2,
repo_root = '/nonexistent/path',
}
assert.has_no.errors(function()
highlight.highlight_hunk(bufnr, ns, hunk, default_opts({ highlights = { context = 25 } }))
end)
local extmarks = get_extmarks(bufnr)
assert.is_true(#extmarks > 0)
delete_buffer(bufnr)
end)
end)
describe('diff header highlighting', function()
@ -1086,6 +1180,7 @@ describe('highlight', function()
highlights = {
background = false,
gutter = false,
context = 0,
treesitter = { enabled = true, max_lines = 500 },
vim = { enabled = false, max_lines = 200 },
},
@ -1242,6 +1337,7 @@ describe('highlight', function()
highlights = {
background = false,
gutter = false,
context = 0,
treesitter = { enabled = true, max_lines = 500 },
vim = { enabled = false, max_lines = 200 },
},

79
spec/parser_spec.lua
View file

@ -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)