From 676f89b28f86c9b64638790965844c1f77830254 Mon Sep 17 00:00:00 2001
From: Uko Kokņevičs
Date: Sun, 2 Jan 2022 09:15:10 +0200
Subject: Make <untab> actually do something

---
 src/Buffer.zig    | 44 ++++++++++++++++++++++++++++++++++----------
 src/Row.zig       |  8 ++------
 src/key_state.zig |  4 +++-
 3 files changed, 39 insertions(+), 17 deletions(-)

diff --git a/src/Buffer.zig b/src/Buffer.zig
index ce2212c..7f3043b 100644
--- a/src/Buffer.zig
+++ b/src/Buffer.zig
@@ -291,6 +291,14 @@ pub fn goToLine(self: *Buffer, editor: *Editor) !void {
     }
 }
 
+pub fn indent(self: *Buffer) !void {
+    if (self.config.hard_tabs) {
+        return self.insertChar('\t');
+    } else {
+        return self.insertNChars(' ', self.config.tab_stop - self.cx % self.config.tab_stop);
+    }
+}
+
 pub fn insertChar(self: *Buffer, char: u8) !void {
     if (self.cy == self.rows.items.len) {
         try self.insertRow(self.rows.items.len, "");
@@ -320,8 +328,8 @@ pub fn insertNewline(self: *Buffer) !void {
 
     var row = &self.rows.items[self.cy];
 
-    const indentation = try row.indentation(self.allocator);
-    defer self.allocator.free(indentation);
+    const indentation_size = row.indentationSize();
+    const indentation = row.data.items[0..indentation_size];
 
     try self.insertRow(self.cy + 1, indentation);
     row = &self.rows.items[self.cy];
@@ -349,14 +357,6 @@ pub fn insertRow(self: *Buffer, at: usize, data: []const u8) !void {
     self.dirty = true;
 }
 
-pub fn insertTab(self: *Buffer) !void {
-    if (self.config.hard_tabs) {
-        return self.insertChar('\t');
-    } else {
-        return self.insertNChars(' ', self.config.tab_stop - self.cx % self.config.tab_stop);
-    }
-}
-
 pub fn killLine(self: *Buffer) !void {
     return self.deleteRow(self.cy);
 }
@@ -537,6 +537,30 @@ pub fn selectSyntaxHighlighting(self: *Buffer) !void {
     }
 }
 
+pub fn unindent(self: *Buffer) !void {
+    if (self.cy == self.rows.items.len) {
+        return;
+    }
+
+    // Find the end of starting whitespace
+    const row = &self.rows.items[self.cy];
+    var indentation_size = row.indentationSize();
+    if (indentation_size == 0) {
+        return;
+    }
+
+    const indentation_rsize = row.cxToRx(self.config, indentation_size);
+    const desired_rsize = indentation_rsize - 1 - (indentation_rsize - 1) % self.config.tab_stop;
+    const desired_size = row.rxToCx(self.config, desired_rsize);
+
+    self.cx -= indentation_size - desired_size;
+
+    // TODO: ArrayList needs orderedRemoveNItems
+    while (indentation_size > desired_size) : (indentation_size -= 1) {
+        try row.deleteChar(self, desired_size);
+    }
+}
+
 fn printWithLeftPadding(
     allocator: Allocator,
     writer: anytype,
diff --git a/src/Row.zig b/src/Row.zig
index a47be6a..d1de2aa 100644
--- a/src/Row.zig
+++ b/src/Row.zig
@@ -83,10 +83,7 @@ pub fn deleteChar(self: *Row, buf: *Buffer, at: usize) !void {
     try self.update(buf);
 }
 
-pub fn indentation(self: Row, allocator: Allocator) ![]u8 {
-    var str = ArrayList(u8).init(allocator);
-    defer str.deinit();
-
+pub fn indentationSize(self: Row) usize {
     var idx: usize = 0;
     while (idx < self.data.items.len) : (idx += 1) {
         if (!std.ascii.isBlank(self.data.items[idx])) {
@@ -94,8 +91,7 @@ pub fn indentation(self: Row, allocator: Allocator) ![]u8 {
         }
     }
 
-    try str.appendSlice(self.data.items[0..idx]);
-    return str.toOwnedSlice();
+    return idx;
 }
 
 pub fn insertChar(self: *Row, buf: *Buffer, at: usize, char: u8) !void {
diff --git a/src/key_state.zig b/src/key_state.zig
index 2cb9988..818dded 100644
--- a/src/key_state.zig
+++ b/src/key_state.zig
@@ -96,7 +96,7 @@ pub fn defaultState(editor: *Editor, buf: *Buffer, key: Key) Error!void {
         // TODO: C-h help
 
         // tab
-        Key.ctrl('i') => try buf.insertTab(),
+        Key.ctrl('i') => try buf.indent(),
         // line feed
         Key.ctrl('j') => try buf.insertNewline(),
         Key.ctrl('k') => try buf.killLine(),
@@ -122,6 +122,8 @@ pub fn defaultState(editor: *Editor, buf: *Buffer, key: Key) Error!void {
         },
 
         // ========== <*> ==========
+        Key.untab => try buf.unindent(),
+
         else => {
             if (@enumToInt(key) <= @enumToInt(Key.max_char)) {
                 const char = @intCast(u8, @enumToInt(key));
-- 
cgit v1.2.3