Commit 8dd078b99a

@@ -65,15 +65,9 @@ pub const Buffer = struct {
     }
 
     pub fn allocPrint(allocator: *Allocator, comptime format: []const u8, args: var) !Buffer {
-        const countSize = struct {
-            fn countSize(size: *usize, bytes: []const u8) (error{}!void) {
-                size.* += bytes.len;
-            }
-        }.countSize;
-        var size: usize = 0;
-        std.fmt.format(&size, error{}, countSize, format, args) catch |err| switch (err) {};
+        const size = std.fmtstream.count(format, args);
         var self = try Buffer.initSize(allocator, size);
-        assert((std.fmt.bufPrint(self.list.items, format, args) catch unreachable).len == size);
+        assert((std.fmtstream.bufPrint(self.list.items, format, args) catch unreachable).len == size);
         return self;
     }
 
@@ -155,7 +149,7 @@ pub const Buffer = struct {
     }
 
     pub fn print(self: *Buffer, comptime fmt: []const u8, args: var) !void {
-        return std.fmt.format(self, error{OutOfMemory}, Buffer.append, fmt, args);
+        return self.outStream().print(fmt, args);
     }
 
     pub fn outStream(self: *Buffer) std.io.OutStream(*Buffer, error{OutOfMemory}, appendWrite) {

@@ -1080,14 +1080,17 @@ pub fn bufPrint(buf: []u8, comptime fmt: []const u8, args: var) BufPrintError![]
     return buf[0..fbs.pos];
 }
 
-pub const AllocPrintError = error{OutOfMemory};
-
-pub fn allocPrint(allocator: *mem.Allocator, comptime fmt: []const u8, args: var) AllocPrintError![]u8 {
-    // Count the characters we need to preallocate
+// Count the characters needed for format. Useful for preallocating memory
+pub fn count(comptime fmt: []const u8, args: var) usize {
     var counting_stream = std.io.countingOutStream(std.io.null_out_stream);
     format(counting_stream.outStream(), fmt, args) catch |err| switch (err) {};
+    return counting_stream.bytes_written;
+}
 
-    const buf = try allocator.alloc(u8, counting_stream.bytes_written);
+pub const AllocPrintError = error{OutOfMemory};
+
+pub fn allocPrint(allocator: *mem.Allocator, comptime fmt: []const u8, args: var) AllocPrintError![]u8 {
+    const buf = try allocator.alloc(u8, count(fmt, args));
     return bufPrint(buf, fmt, args) catch |err| switch (err) {
         error.BufferTooSmall => unreachable, // we just counted the size above
     };