feat: ignore whitespace option (diffopt+=iwhite support)

README.md

@@ -88,6 +88,7 @@ https://github.com/user-attachments/assets/64c41f01-dffe-4318-bce4-16eec8de356e
     diff = {
       disable_inlay_hints = true,         -- Disable inlay hints in diff windows for cleaner view
       max_computation_time_ms = 5000,     -- Maximum time for diff computation (VSCode default)
+      ignore_trim_whitespace = false,     -- Ignore leading/trailing whitespace changes (like diffopt+=iwhite)
       hide_merge_artifacts = false,       -- Hide merge tool temp files (*.orig, *.BACKUP.*, *.BASE.*, *.LOCAL.*, *.REMOTE.*)
       original_position = "left",         -- Position of original (old) content: "left" or "right"
       conflict_ours_position = "right",   -- Position of ours (:2) in conflict view: "left" or "right"

VERSION

@@ -1 +1 @@
-2.19.0
+2.20.0

lua/codediff/config.lua

@@ -31,6 +31,7 @@ M.defaults = {
   diff = {
     disable_inlay_hints = true, -- Disable inlay hints in diff windows for cleaner view
     max_computation_time_ms = 5000, -- Maximum time for diff computation (5 seconds, VSCode default)
+    ignore_trim_whitespace = false, -- Ignore leading/trailing whitespace changes (like diffopt+=iwhite)
     hide_merge_artifacts = false, -- Hide merge tool temp files (*.orig, *.BACKUP.*, *.BASE.*, *.LOCAL.*, *.REMOTE.*)
     original_position = "left", -- Position of original (old) content: "left" or "right"
     conflict_ours_position = "right", -- Position of ours (:2) in conflict view: "left" or "right" (independent of original_position)

lua/codediff/ui/auto_refresh.lua

@@ -89,6 +89,7 @@ local function do_diff_update(bufnr, skip_watcher_check)
     local config = require("codediff.config")
     local diff_options = {
       max_computation_time_ms = config.options.diff.max_computation_time_ms,
+      ignore_trim_whitespace = config.options.diff.ignore_trim_whitespace,
     }
     local lines_diff = diff.compute_diff(original_lines, modified_lines, diff_options)
     if not lines_diff then
@@ -270,6 +271,7 @@ local function do_result_diff_update(bufnr)
   local config = require("codediff.config")
   local diff_options = {
     max_computation_time_ms = config.options.diff.max_computation_time_ms,
+    ignore_trim_whitespace = config.options.diff.ignore_trim_whitespace,
   }
   local lines_diff = diff.compute_diff(base_lines, result_lines, diff_options)
   if not lines_diff then

lua/codediff/ui/lifecycle/state.lua

@@ -156,7 +156,11 @@ local function resume_diff(tabpage)
   if need_recompute or not diff.stored_diff_result then
     -- Buffer or file changed, recompute diff
     local diff_module = require("codediff.core.diff")
-    lines_diff = diff_module.compute_diff(original_lines, modified_lines)
+    local config = require("codediff.config")
+    lines_diff = diff_module.compute_diff(original_lines, modified_lines, {
+      max_computation_time_ms = config.options.diff.max_computation_time_ms,
+      ignore_trim_whitespace = config.options.diff.ignore_trim_whitespace,
+    })
     diff_was_recomputed = true
 
     if lines_diff then

lua/codediff/ui/view/render.lua

@@ -22,6 +22,7 @@ function M.compute_and_render(
   -- Compute diff
   local diff_options = {
     max_computation_time_ms = config.options.diff.max_computation_time_ms,
+    ignore_trim_whitespace = config.options.diff.ignore_trim_whitespace,
   }
   local lines_diff = diff_module.compute_diff(original_lines, modified_lines, diff_options)
   if not lines_diff then
@@ -102,6 +103,7 @@ end
 function M.compute_and_render_conflict(original_buf, modified_buf, base_lines, original_lines, modified_lines, original_win, modified_win, auto_scroll_to_first_hunk)
   local diff_options = {
     max_computation_time_ms = config.options.diff.max_computation_time_ms,
+    ignore_trim_whitespace = config.options.diff.ignore_trim_whitespace,
   }
 
   -- Compute base -> original (incoming) diff

tests/ignore_whitespace_spec.lua

@@ -0,0 +1,65 @@
+-- Test: ignore_trim_whitespace option
+-- Validates that the ignore_trim_whitespace DiffOption works correctly via FFI
+
+local diff = require('codediff.core.diff')
+
+describe("ignore_trim_whitespace", function()
+  it("detects whitespace-only changes when disabled", function()
+    local result = diff.compute_diff(
+      {"  hello", "world"},
+      {"    hello", "world"},
+      { ignore_trim_whitespace = false }
+    )
+    assert.is_true(#result.changes > 0, "Should detect leading whitespace change")
+  end)
+
+  it("ignores leading whitespace changes when enabled", function()
+    local result = diff.compute_diff(
+      {"  hello", "world"},
+      {"    hello", "world"},
+      { ignore_trim_whitespace = true }
+    )
+    assert.equal(0, #result.changes, "Should ignore leading whitespace difference")
+  end)
+
+  it("ignores trailing whitespace changes when enabled", function()
+    local result = diff.compute_diff(
+      {"hello  ", "world"},
+      {"hello    ", "world"},
+      { ignore_trim_whitespace = true }
+    )
+    assert.equal(0, #result.changes, "Should ignore trailing whitespace difference")
+  end)
+
+  it("still detects content changes when whitespace is ignored", function()
+    local result = diff.compute_diff(
+      {"  hello", "world"},
+      {"  goodbye", "world"},
+      { ignore_trim_whitespace = true }
+    )
+    assert.is_true(#result.changes > 0, "Should still detect non-whitespace changes")
+  end)
+
+  it("ignores indentation-only changes across multiple lines", function()
+    local result = diff.compute_diff(
+      {"function foo()", "  return 1", "end"},
+      {"function foo()", "    return 1", "end"},
+      { ignore_trim_whitespace = true }
+    )
+    assert.equal(0, #result.changes, "Should ignore indentation-only differences")
+  end)
+
+  it("defaults to false when not specified", function()
+    local with_default = diff.compute_diff(
+      {"  hello"},
+      {"    hello"}
+    )
+    local with_false = diff.compute_diff(
+      {"  hello"},
+      {"    hello"},
+      { ignore_trim_whitespace = false }
+    )
+    assert.equal(#with_default.changes, #with_false.changes,
+      "Default behavior should match ignore_trim_whitespace=false")
+  end)
+end)