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Convert Buffer to use fmtstream

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This commit is contained in:
Benjamin Feng 2020-02-29 21:43:54 -06:00
parent 2429fdd73b
commit 8dd078b99a
2 changed files with 11 additions and 14 deletions
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12
lib/std/buffer.zig
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@ -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) {

13
lib/std/fmtstream.zig
View File

@ -1080,14 +1080,17 @@ pub fn bufPrint(buf: []u8, comptime fmt: []const u8, args: var) BufPrintError![]
return buf[0..fbs.pos];
}
// 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;
}
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
var counting_stream = std.io.countingOutStream(std.io.null_out_stream);
format(counting_stream.outStream(), fmt, args) catch |err| switch (err) {};
const buf = try allocator.alloc(u8, counting_stream.bytes_written);
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
};