alright

Former-commit-id: ab73c7b323

src/strings.zig

@@ -9,6 +9,46 @@ pub const MutableString = mutable.MutableString;
 
 pub const eql = std.meta.eql;
 
+pub fn NewStringBuilder(comptime size: usize) type {
+    return struct {
+        const This = @This();
+        buffer: [size + 1]u8 = undefined,
+        remain: []u8 = undefined,
+
+        pub fn init() This {
+            var instance = This{};
+            instance.load();
+            return instance;
+        }
+
+        fn load(this: *This) void {
+            this.remain = (&this.buffer)[0..size];
+        }
+
+        pub fn append(this: *This, str: string) void {
+            std.mem.copy(u8, this.remain, str);
+            this.remain = this.remain[str.len..];
+        }
+
+        pub fn str(this: *This) string {
+            var buf = this.buffer[0 .. @ptrToInt(this.remain.ptr) - @ptrToInt(&this.buffer)];
+            // Always leave a sentinel so that anything that expects a sentinel Just Works
+            // specifically, the reason for this is so C-based APIs can be used without an extra copy.
+            // one byte is cheap...right?
+            this.buffer[buf.len] = 0;
+            return buf;
+        }
+
+        pub fn pop(this: *This, count: usize) string {
+            this.remain = this.buffer[0 .. @ptrToInt(this.remain.ptr) - @ptrToInt(&this.buffer) - count];
+        }
+
+        pub fn reset(this: *This) void {
+            this.load();
+        }
+    };
+}
+
 pub fn nql(a: anytype, b: @TypeOf(a)) bool {
     return !eql(a, b);
 }