zig/std/fmt/index.zig

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const std = @import("../index.zig");
const math = std.math;
const debug = std.debug;
const assert = debug.assert;
const mem = std.mem;
const builtin = @import("builtin");
const errol3 = @import("errol/index.zig").errol3;
const max_int_digits = 65;
const State = enum { // TODO put inside format function and make sure the name and debug info is correct
Start,
OpenBrace,
CloseBrace,
Integer,
IntegerWidth,
Float,
FloatWidth,
Character,
Buf,
BufWidth,
};
/// Renders fmt string with args, calling output with slices of bytes.
/// If `output` returns an error, the error is returned from `format` and
/// `output` is not called again.
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pub fn format(context: var, comptime Errors: type, output: fn(@typeOf(context), []const u8) Errors!void,
comptime fmt: []const u8, args: ...) Errors!void
{
comptime var start_index = 0;
comptime var state = State.Start;
comptime var next_arg = 0;
comptime var radix = 0;
comptime var uppercase = false;
comptime var width = 0;
comptime var width_start = 0;
inline for (fmt) |c, i| {
switch (state) {
State.Start => switch (c) {
'{' => {
if (start_index < i) {
try output(context, fmt[start_index..i]);
}
state = State.OpenBrace;
},
'}' => {
if (start_index < i) {
try output(context, fmt[start_index..i]);
}
state = State.CloseBrace;
},
else => {},
},
State.OpenBrace => switch (c) {
'{' => {
state = State.Start;
start_index = i;
},
'}' => {
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try formatValue(args[next_arg], context, Errors, output);
next_arg += 1;
state = State.Start;
start_index = i + 1;
},
'd' => {
radix = 10;
uppercase = false;
width = 0;
state = State.Integer;
},
'x' => {
radix = 16;
uppercase = false;
width = 0;
state = State.Integer;
},
'X' => {
radix = 16;
uppercase = true;
width = 0;
state = State.Integer;
},
'c' => {
state = State.Character;
},
's' => {
state = State.Buf;
},'.' => {
state = State.Float;
},
else => @compileError("Unknown format character: " ++ []u8{c}),
},
State.Buf => switch (c) {
'}' => {
return output(context, args[next_arg]);
},
'0' ... '9' => {
width_start = i;
state = State.BufWidth;
},
else => @compileError("Unexpected character in format string: " ++ []u8{c}),
},
State.CloseBrace => switch (c) {
'}' => {
state = State.Start;
start_index = i;
},
else => @compileError("Single '}' encountered in format string"),
},
State.Integer => switch (c) {
'}' => {
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try formatInt(args[next_arg], radix, uppercase, width, context, Errors, output);
next_arg += 1;
state = State.Start;
start_index = i + 1;
},
'0' ... '9' => {
width_start = i;
state = State.IntegerWidth;
},
else => @compileError("Unexpected character in format string: " ++ []u8{c}),
},
State.IntegerWidth => switch (c) {
'}' => {
width = comptime (parseUnsigned(usize, fmt[width_start..i], 10) catch unreachable);
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try formatInt(args[next_arg], radix, uppercase, width, context, Errors, output);
next_arg += 1;
state = State.Start;
start_index = i + 1;
},
'0' ... '9' => {},
else => @compileError("Unexpected character in format string: " ++ []u8{c}),
},
State.Float => switch (c) {
'}' => {
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try formatFloatDecimal(args[next_arg], 0, context, Errors, output);
next_arg += 1;
state = State.Start;
start_index = i + 1;
},
'0' ... '9' => {
width_start = i;
state = State.FloatWidth;
},
else => @compileError("Unexpected character in format string: " ++ []u8{c}),
},
State.FloatWidth => switch (c) {
'}' => {
width = comptime (parseUnsigned(usize, fmt[width_start..i], 10) catch unreachable);
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try formatFloatDecimal(args[next_arg], width, context, Errors, output);
next_arg += 1;
state = State.Start;
start_index = i + 1;
},
'0' ... '9' => {},
else => @compileError("Unexpected character in format string: " ++ []u8{c}),
},
State.BufWidth => switch (c) {
'}' => {
width = comptime (parseUnsigned(usize, fmt[width_start..i], 10) catch unreachable);
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try formatBuf(args[next_arg], width, context, Errors, output);
next_arg += 1;
state = State.Start;
start_index = i + 1;
},
'0' ... '9' => {},
else => @compileError("Unexpected character in format string: " ++ []u8{c}),
},
State.Character => switch (c) {
'}' => {
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try formatAsciiChar(args[next_arg], context, Errors, output);
next_arg += 1;
state = State.Start;
start_index = i + 1;
},
else => @compileError("Unexpected character in format string: " ++ []u8{c}),
},
}
}
comptime {
if (args.len != next_arg) {
@compileError("Unused arguments");
}
if (state != State.Start) {
@compileError("Incomplete format string: " ++ fmt);
}
}
if (start_index < fmt.len) {
try output(context, fmt[start_index..]);
}
}
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pub fn formatValue(value: var, context: var, comptime Errors: type, output: fn(@typeOf(context), []const u8)Errors!void) Errors!void {
const T = @typeOf(value);
switch (@typeId(T)) {
builtin.TypeId.Int => {
return formatInt(value, 10, false, 0, context, Errors, output);
},
builtin.TypeId.Float => {
return formatFloat(value, context, Errors, output);
},
builtin.TypeId.Void => {
return output(context, "void");
},
builtin.TypeId.Bool => {
return output(context, if (value) "true" else "false");
},
builtin.TypeId.Nullable => {
if (value) |payload| {
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return formatValue(payload, context, Errors, output);
} else {
return output(context, "null");
}
},
builtin.TypeId.ErrorUnion => {
if (value) |payload| {
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return formatValue(payload, context, Errors, output);
} else |err| {
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return formatValue(err, context, Errors, output);
}
},
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builtin.TypeId.ErrorSet => {
try output(context, "error.");
return output(context, @errorName(value));
},
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builtin.TypeId.Pointer => {
if (@typeId(T.Child) == builtin.TypeId.Array and T.Child.Child == u8) {
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return output(context, (*value)[0..]);
} else {
return format(context, Errors, output, "{}@{x}", @typeName(T.Child), @ptrToInt(value));
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}
},
else => if (@canImplicitCast([]const u8, value)) {
const casted_value = ([]const u8)(value);
return output(context, casted_value);
} else {
@compileError("Unable to format type '" ++ @typeName(T) ++ "'");
},
}
}
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pub fn formatAsciiChar(c: u8, context: var, comptime Errors: type, output: fn(@typeOf(context), []const u8)Errors!void) Errors!void {
return output(context, (&c)[0..1]);
}
pub fn formatBuf(buf: []const u8, width: usize,
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context: var, comptime Errors: type, output: fn(@typeOf(context), []const u8)Errors!void) Errors!void
{
try output(context, buf);
var leftover_padding = if (width > buf.len) (width - buf.len) else return;
const pad_byte: u8 = ' ';
while (leftover_padding > 0) : (leftover_padding -= 1) {
try output(context, (&pad_byte)[0..1]);
}
}
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pub fn formatFloat(value: var, context: var, comptime Errors: type, output: fn(@typeOf(context), []const u8)Errors!void) Errors!void {
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var x = f64(value);
// Errol doesn't handle these special cases.
if (math.isNan(x)) {
return output(context, "NaN");
}
if (math.signbit(x)) {
try output(context, "-");
x = -x;
}
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if (math.isPositiveInf(x)) {
return output(context, "Infinity");
}
if (x == 0.0) {
return output(context, "0.0");
}
var buffer: [32]u8 = undefined;
const float_decimal = errol3(x, buffer[0..]);
try output(context, float_decimal.digits[0..1]);
try output(context, ".");
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if (float_decimal.digits.len > 1) {
const num_digits = if (@typeOf(value) == f32)
math.min(usize(9), float_decimal.digits.len)
else
float_decimal.digits.len;
try output(context, float_decimal.digits[1 .. num_digits]);
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} else {
try output(context, "0");
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}
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if (float_decimal.exp != 1) {
try output(context, "e");
try formatInt(float_decimal.exp - 1, 10, false, 0, context, Errors, output);
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}
}
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pub fn formatFloatDecimal(value: var, precision: usize, context: var, comptime Errors: type, output: fn(@typeOf(context), []const u8)Errors!void) Errors!void {
var x = f64(value);
// Errol doesn't handle these special cases.
if (math.isNan(x)) {
return output(context, "NaN");
}
if (math.signbit(x)) {
try output(context, "-");
x = -x;
}
if (math.isPositiveInf(x)) {
return output(context, "Infinity");
}
if (x == 0.0) {
return output(context, "0.0");
}
var buffer: [32]u8 = undefined;
const float_decimal = errol3(x, buffer[0..]);
const num_left_digits = if (float_decimal.exp > 0) usize(float_decimal.exp) else 1;
try output(context, float_decimal.digits[0 .. num_left_digits]);
try output(context, ".");
if (float_decimal.digits.len > 1) {
const num_valid_digtis = if (@typeOf(value) == f32) math.min(usize(7), float_decimal.digits.len)
else
float_decimal.digits.len;
const num_right_digits = if (precision != 0)
math.min(precision, (num_valid_digtis-num_left_digits))
else
num_valid_digtis - num_left_digits;
try output(context, float_decimal.digits[num_left_digits .. (num_left_digits + num_right_digits)]);
} else {
try output(context, "0");
}
}
pub fn formatInt(value: var, base: u8, uppercase: bool, width: usize,
context: var, comptime Errors: type, output: fn(@typeOf(context), []const u8)Errors!void) Errors!void
{
if (@typeOf(value).is_signed) {
return formatIntSigned(value, base, uppercase, width, context, Errors, output);
} else {
return formatIntUnsigned(value, base, uppercase, width, context, Errors, output);
}
}
fn formatIntSigned(value: var, base: u8, uppercase: bool, width: usize,
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context: var, comptime Errors: type, output: fn(@typeOf(context), []const u8)Errors!void) Errors!void
{
const uint = @IntType(false, @typeOf(value).bit_count);
if (value < 0) {
const minus_sign: u8 = '-';
try output(context, (&minus_sign)[0..1]);
const new_value = uint(-(value + 1)) + 1;
const new_width = if (width == 0) 0 else (width - 1);
return formatIntUnsigned(new_value, base, uppercase, new_width, context, Errors, output);
} else if (width == 0) {
return formatIntUnsigned(uint(value), base, uppercase, width, context, Errors, output);
} else {
const plus_sign: u8 = '+';
try output(context, (&plus_sign)[0..1]);
const new_value = uint(value);
const new_width = if (width == 0) 0 else (width - 1);
return formatIntUnsigned(new_value, base, uppercase, new_width, context, Errors, output);
}
}
fn formatIntUnsigned(value: var, base: u8, uppercase: bool, width: usize,
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context: var, comptime Errors: type, output: fn(@typeOf(context), []const u8)Errors!void) Errors!void
{
// max_int_digits accounts for the minus sign. when printing an unsigned
// number we don't need to do that.
var buf: [max_int_digits - 1]u8 = undefined;
var a = if (@sizeOf(@typeOf(value)) == 1) u8(value) else value;
var index: usize = buf.len;
while (true) {
const digit = a % base;
index -= 1;
buf[index] = digitToChar(u8(digit), uppercase);
a /= base;
if (a == 0)
break;
}
const digits_buf = buf[index..];
const padding = if (width > digits_buf.len) (width - digits_buf.len) else 0;
if (padding > index) {
const zero_byte: u8 = '0';
var leftover_padding = padding - index;
while (true) {
try output(context, (&zero_byte)[0..1]);
leftover_padding -= 1;
if (leftover_padding == 0)
break;
}
mem.set(u8, buf[0..index], '0');
return output(context, buf);
} else {
const padded_buf = buf[index - padding..];
mem.set(u8, padded_buf[0..padding], '0');
return output(context, padded_buf);
}
}
pub fn formatIntBuf(out_buf: []u8, value: var, base: u8, uppercase: bool, width: usize) usize {
var context = FormatIntBuf {
.out_buf = out_buf,
.index = 0,
};
formatInt(value, base, uppercase, width, &context, error{}, formatIntCallback) catch unreachable;
return context.index;
}
const FormatIntBuf = struct {
out_buf: []u8,
index: usize,
};
fn formatIntCallback(context: &FormatIntBuf, bytes: []const u8) (error{}!void) {
mem.copy(u8, context.out_buf[context.index..], bytes);
context.index += bytes.len;
}
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pub fn parseInt(comptime T: type, buf: []const u8, radix: u8) !T {
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if (!T.is_signed)
return parseUnsigned(T, buf, radix);
if (buf.len == 0)
return T(0);
if (buf[0] == '-') {
return math.negate(try parseUnsigned(T, buf[1..], radix));
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} else if (buf[0] == '+') {
return parseUnsigned(T, buf[1..], radix);
} else {
return parseUnsigned(T, buf, radix);
}
}
test "fmt.parseInt" {
assert((parseInt(i32, "-10", 10) catch unreachable) == -10);
assert((parseInt(i32, "+10", 10) catch unreachable) == 10);
assert(if (parseInt(i32, " 10", 10)) |_| false else |err| err == error.InvalidCharacter);
assert(if (parseInt(i32, "10 ", 10)) |_| false else |err| err == error.InvalidCharacter);
assert(if (parseInt(u32, "-10", 10)) |_| false else |err| err == error.InvalidCharacter);
assert((parseInt(u8, "255", 10) catch unreachable) == 255);
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assert(if (parseInt(u8, "256", 10)) |_| false else |err| err == error.Overflow);
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}
const ParseUnsignedError = error {
/// The result cannot fit in the type specified
Overflow,
/// The input had a byte that was not a digit
InvalidCharacter,
};
pub fn parseUnsigned(comptime T: type, buf: []const u8, radix: u8) ParseUnsignedError!T {
var x: T = 0;
for (buf) |c| {
const digit = try charToDigit(c, radix);
x = try math.mul(T, x, radix);
x = try math.add(T, x, digit);
}
return x;
}
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pub fn charToDigit(c: u8, radix: u8) (error{InvalidCharacter}!u8) {
const value = switch (c) {
'0' ... '9' => c - '0',
'A' ... 'Z' => c - 'A' + 10,
'a' ... 'z' => c - 'a' + 10,
else => return error.InvalidCharacter,
};
if (value >= radix)
return error.InvalidCharacter;
return value;
}
fn digitToChar(digit: u8, uppercase: bool) u8 {
return switch (digit) {
0 ... 9 => digit + '0',
10 ... 35 => digit + ((if (uppercase) u8('A') else u8('a')) - 10),
else => unreachable,
};
}
const BufPrintContext = struct {
remaining: []u8,
};
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fn bufPrintWrite(context: &BufPrintContext, bytes: []const u8) !void {
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if (context.remaining.len < bytes.len) return error.BufferTooSmall;
mem.copy(u8, context.remaining, bytes);
context.remaining = context.remaining[bytes.len..];
}
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pub fn bufPrint(buf: []u8, comptime fmt: []const u8, args: ...) ![]u8 {
var context = BufPrintContext { .remaining = buf, };
try format(&context, error{BufferTooSmall}, bufPrintWrite, fmt, args);
return buf[0..buf.len - context.remaining.len];
}
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pub fn allocPrint(allocator: &mem.Allocator, comptime fmt: []const u8, args: ...) ![]u8 {
var size: usize = 0;
format(&size, error{}, countSize, fmt, args) catch |err| switch (err) {};
const buf = try allocator.alloc(u8, size);
return bufPrint(buf, fmt, args);
}
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fn countSize(size: &usize, bytes: []const u8) (error{}!void) {
*size += bytes.len;
}
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test "buf print int" {
var buffer: [max_int_digits]u8 = undefined;
const buf = buffer[0..];
assert(mem.eql(u8, bufPrintIntToSlice(buf, i32(-12345678), 2, false, 0), "-101111000110000101001110"));
assert(mem.eql(u8, bufPrintIntToSlice(buf, i32(-12345678), 10, false, 0), "-12345678"));
assert(mem.eql(u8, bufPrintIntToSlice(buf, i32(-12345678), 16, false, 0), "-bc614e"));
assert(mem.eql(u8, bufPrintIntToSlice(buf, i32(-12345678), 16, true, 0), "-BC614E"));
assert(mem.eql(u8, bufPrintIntToSlice(buf, u32(12345678), 10, true, 0), "12345678"));
assert(mem.eql(u8, bufPrintIntToSlice(buf, u32(666), 10, false, 6), "000666"));
assert(mem.eql(u8, bufPrintIntToSlice(buf, u32(0x1234), 16, false, 6), "001234"));
assert(mem.eql(u8, bufPrintIntToSlice(buf, u32(0x1234), 16, false, 1), "1234"));
assert(mem.eql(u8, bufPrintIntToSlice(buf, i32(42), 10, false, 3), "+42"));
assert(mem.eql(u8, bufPrintIntToSlice(buf, i32(-42), 10, false, 3), "-42"));
}
fn bufPrintIntToSlice(buf: []u8, value: var, base: u8, uppercase: bool, width: usize) []u8 {
return buf[0..formatIntBuf(buf, value, base, uppercase, width)];
}
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test "parse u64 digit too big" {
_ = parseUnsigned(u64, "123a", 10) catch |err| {
if (err == error.InvalidCharacter) return;
unreachable;
};
unreachable;
}
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test "parse unsigned comptime" {
comptime {
assert((try parseUnsigned(usize, "2", 10)) == 2);
}
}
test "fmt.format" {
{
var buf1: [32]u8 = undefined;
const value: ?i32 = 1234;
const result = try bufPrint(buf1[0..], "nullable: {}\n", value);
assert(mem.eql(u8, result, "nullable: 1234\n"));
}
{
var buf1: [32]u8 = undefined;
const value: ?i32 = null;
const result = try bufPrint(buf1[0..], "nullable: {}\n", value);
assert(mem.eql(u8, result, "nullable: null\n"));
}
{
var buf1: [32]u8 = undefined;
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const value: error!i32 = 1234;
const result = try bufPrint(buf1[0..], "error union: {}\n", value);
assert(mem.eql(u8, result, "error union: 1234\n"));
}
{
var buf1: [32]u8 = undefined;
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const value: error!i32 = error.InvalidChar;
const result = try bufPrint(buf1[0..], "error union: {}\n", value);
assert(mem.eql(u8, result, "error union: error.InvalidChar\n"));
}
{
var buf1: [32]u8 = undefined;
const value: u3 = 0b101;
const result = try bufPrint(buf1[0..], "u3: {}\n", value);
assert(mem.eql(u8, result, "u3: 5\n"));
}
{
// Dummy field because of https://github.com/zig-lang/zig/issues/557.
const Struct = struct {
unused: u8,
};
var buf1: [32]u8 = undefined;
const value = Struct {
.unused = 42,
};
const result = try bufPrint(buf1[0..], "pointer: {}\n", &value);
assert(mem.startsWith(u8, result, "pointer: Struct@"));
}
// TODO get these tests passing in release modes
// https://github.com/zig-lang/zig/issues/564
if (builtin.mode == builtin.Mode.Debug) {
{
var buf1: [32]u8 = undefined;
const value: f32 = 12.34;
const result = try bufPrint(buf1[0..], "f32: {}\n", value);
assert(mem.eql(u8, result, "f32: 1.23400001e1\n"));
}
{
var buf1: [32]u8 = undefined;
const value: f64 = -12.34e10;
const result = try bufPrint(buf1[0..], "f64: {}\n", value);
assert(mem.eql(u8, result, "f64: -1.234e11\n"));
}
{
var buf1: [32]u8 = undefined;
const result = try bufPrint(buf1[0..], "f64: {}\n", math.nan_f64);
assert(mem.eql(u8, result, "f64: NaN\n"));
}
{
var buf1: [32]u8 = undefined;
const result = try bufPrint(buf1[0..], "f64: {}\n", math.inf_f64);
assert(mem.eql(u8, result, "f64: Infinity\n"));
}
{
var buf1: [32]u8 = undefined;
const result = try bufPrint(buf1[0..], "f64: {}\n", -math.inf_f64);
assert(mem.eql(u8, result, "f64: -Infinity\n"));
}
{
var buf1: [32]u8 = undefined;
const value: f32 = 1.1234;
const result = try bufPrint(buf1[0..], "f32: {.1}\n", value);
assert(mem.eql(u8, result, "f32: 1.1\n"));
}
{
var buf1: [32]u8 = undefined;
const value: f32 = 1234.567;
const result = try bufPrint(buf1[0..], "f32: {.2}\n", value);
assert(mem.eql(u8, result, "f32: 1234.56\n"));
}
{
var buf1: [32]u8 = undefined;
const value: f32 = -11.1234;
const result = try bufPrint(buf1[0..], "f32: {.4}\n", value);
// -11.1234 is converted to f64 -11.12339... internally (errol3() function takes f64).
// -11.12339... is truncated to -11.1233
assert(mem.eql(u8, result, "f32: -11.1233\n"));
}
{
var buf1: [32]u8 = undefined;
const value: f32 = 91.12345;
const result = try bufPrint(buf1[0..], "f32: {.}\n", value);
assert(mem.eql(u8, result, "f32: 91.12345\n"));
}
{
var buf1: [32]u8 = undefined;
const value: f64 = 91.12345678901235;
const result = try bufPrint(buf1[0..], "f64: {.10}\n", value);
assert(mem.eql(u8, result, "f64: 91.1234567890\n"));
}
}
}
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pub fn trim(buf: []const u8) []const u8 {
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var start: usize = 0;
while (start < buf.len and isWhiteSpace(buf[start])) : (start += 1) { }
var end: usize = buf.len;
while (true) {
if (end > start) {
const new_end = end - 1;
if (isWhiteSpace(buf[new_end])) {
end = new_end;
continue;
}
}
break;
}
return buf[start..end];
}
test "fmt.trim" {
assert(mem.eql(u8, "abc", trim("\n abc \t")));
assert(mem.eql(u8, "", trim(" ")));
assert(mem.eql(u8, "", trim("")));
assert(mem.eql(u8, "abc", trim(" abc")));
assert(mem.eql(u8, "abc", trim("abc ")));
}
pub fn isWhiteSpace(byte: u8) bool {
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return switch (byte) {
' ', '\t', '\n', '\r' => true,
else => false,
};
}