zig/std/fmt/index.zig
Andrew Kelley 7f0620a20f partial implementation of printing floating point numbers with errol3
also add bitCast builtin function. closes #387
2017-06-14 00:24:25 -04:00

471 lines
16 KiB
Zig

const math = @import("../math/index.zig");
const debug = @import("../debug.zig");
const assert = debug.assert;
const mem = @import("../mem.zig");
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,
Character,
Buf,
BufWidth,
};
/// Renders fmt string with args, calling output with slices of bytes.
/// Return false from output function and output will not be called again.
/// Returns false if output ever returned false, true otherwise.
pub fn format(context: var, output: fn(@typeOf(context), []const u8)->bool,
comptime fmt: []const u8, args: ...) -> bool
{
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) {
'{' => {
// TODO if you make this an if statement with `and` then it breaks
if (start_index < i) {
if (!output(context, fmt[start_index..i]))
return false;
}
state = State.OpenBrace;
},
'}' => {
if (start_index < i) {
if (!output(context, fmt[start_index..i]))
return false;
}
state = State.CloseBrace;
},
else => {},
},
State.OpenBrace => switch (c) {
'{' => {
state = State.Start;
start_index = i;
},
'}' => {
if (!formatValue(args[next_arg], context, output))
return false;
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;
},
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) {
'}' => {
if (!formatInt(args[next_arg], radix, uppercase, width, context, output))
return false;
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);
if (!formatInt(args[next_arg], radix, uppercase, width, context, output))
return false;
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);
if (!formatBuf(args[next_arg], width, context, output))
return false;
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) {
'}' => {
if (!formatAsciiChar(args[next_arg], context, output))
return false;
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) {
if (!output(context, fmt[start_index..]))
return false;
}
return true;
}
pub fn formatValue(value: var, context: var, output: fn(@typeOf(context), []const u8)->bool) -> bool {
const T = @typeOf(value);
switch (@typeId(T)) {
builtin.TypeId.Int => {
return formatInt(value, 10, false, 0, context, output);
},
builtin.TypeId.Float => {
return formatFloat(value, context, 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| {
return formatValue(payload, context, output);
} else {
return output(context, "null");
}
},
builtin.TypeId.ErrorUnion => {
if (value) |payload| {
return formatValue(payload, context, output);
} else |err| {
return formatValue(err, context, output);
}
},
builtin.TypeId.Error => {
if (!output(context, "error."))
return false;
return output(context, @errorName(value));
},
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) ++ "'");
},
}
}
pub fn formatAsciiChar(c: u8, context: var, output: fn(@typeOf(context), []const u8)->bool) -> bool {
return output(context, (&c)[0..1]);
}
pub fn formatBuf(buf: []const u8, width: usize,
context: var, output: fn(@typeOf(context), []const u8)->bool) -> bool
{
if (!output(context, buf))
return false;
var leftover_padding = if (width > buf.len) (width - buf.len) else return true;
const pad_byte: u8 = ' ';
while (leftover_padding > 0) : (leftover_padding -= 1) {
if (!output(context, (&pad_byte)[0..1]))
return false;
}
return true;
}
pub fn formatFloat(value: var, context: var, output: fn(@typeOf(context), []const u8)->bool) -> bool {
var buffer: [20]u8 = undefined;
const float_decimal = errol3(f64(value), buffer[0..]);
if (!output(context, float_decimal.digits[0..1]))
return false;
if (!output(context, "."))
return false;
if (!output(context, float_decimal.digits[1..]))
return false;
if (!output(context, "e"))
return false;
if (!formatInt(float_decimal.exp, 10, false, 0, context, output))
return false;
return true;
}
pub fn formatInt(value: var, base: u8, uppercase: bool, width: usize,
context: var, output: fn(@typeOf(context), []const u8)->bool) -> bool
{
if (@typeOf(value).is_signed) {
return formatIntSigned(value, base, uppercase, width, context, output);
} else {
return formatIntUnsigned(value, base, uppercase, width, context, output);
}
}
fn formatIntSigned(value: var, base: u8, uppercase: bool, width: usize,
context: var, output: fn(@typeOf(context), []const u8)->bool) -> bool
{
const uint = @IntType(false, @typeOf(value).bit_count);
if (value < 0) {
const minus_sign: u8 = '-';
if (!output(context, (&minus_sign)[0..1]))
return false;
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, output);
} else if (width == 0) {
return formatIntUnsigned(uint(value), base, uppercase, width, context, output);
} else {
const plus_sign: u8 = '+';
if (!output(context, (&plus_sign)[0..1]))
return false;
const new_value = uint(value);
const new_width = if (width == 0) 0 else (width - 1);
return formatIntUnsigned(new_value, base, uppercase, new_width, context, output);
}
}
fn formatIntUnsigned(value: var, base: u8, uppercase: bool, width: usize,
context: var, output: fn(@typeOf(context), []const u8)->bool) -> bool
{
// 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 = 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) {
if (!output(context, (&zero_byte)[0..1]))
return false;
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, formatIntCallback);
return context.index;
}
const FormatIntBuf = struct {
out_buf: []u8,
index: usize,
};
fn formatIntCallback(context: &FormatIntBuf, bytes: []const u8) -> bool {
mem.copy(u8, context.out_buf[context.index..], bytes);
context.index += bytes.len;
return true;
}
pub fn parseUnsigned(comptime T: type, buf: []const u8, radix: u8) -> %T {
var x: T = 0;
for (buf) |c| {
const digit = %return charToDigit(c, radix);
x = %return math.mul(T, x, radix);
x = %return math.add(T, x, digit);
}
return x;
}
error InvalidChar;
fn charToDigit(c: u8, radix: u8) -> %u8 {
const value = switch (c) {
'0' ... '9' => c - '0',
'A' ... 'Z' => c - 'A' + 10,
'a' ... 'z' => c - 'a' + 10,
else => return error.InvalidChar,
};
if (value >= radix)
return error.InvalidChar;
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,
};
fn bufPrintWrite(context: &BufPrintContext, bytes: []const u8) -> bool {
mem.copy(u8, context.remaining, bytes);
context.remaining = context.remaining[bytes.len..];
return true;
}
pub fn bufPrint(buf: []u8, comptime fmt: []const u8, args: ...) -> []u8 {
var context = BufPrintContext { .remaining = buf, };
_ = format(&context, bufPrintWrite, fmt, args);
return buf[0..buf.len - context.remaining.len];
}
pub fn allocPrint(allocator: &mem.Allocator, comptime fmt: []const u8, args: ...) -> %[]u8 {
var size: usize = 0;
_ = format(&size, countSize, fmt, args);
const buf = %return allocator.alloc(u8, size);
return bufPrint(buf, fmt, args);
}
fn countSize(size: &usize, bytes: []const u8) -> bool {
*size += bytes.len;
return true;
}
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)];
}
test "parse u64 digit too big" {
_ = parseUnsigned(u64, "123a", 10) %% |err| {
if (err == error.InvalidChar) return;
unreachable;
};
unreachable;
}
test "parse unsigned comptime" {
comptime {
assert(%%parseUnsigned(usize, "2", 10) == 2);
}
}
test "fmt.format" {
{
var buf1: [32]u8 = undefined;
const value: ?i32 = 1234;
const result = 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 = bufPrint(buf1[0..], "nullable: {}\n", value);
assert(mem.eql(u8, result, "nullable: null\n"));
}
{
var buf1: [32]u8 = undefined;
const value: %i32 = 1234;
const result = bufPrint(buf1[0..], "error union: {}\n", value);
assert(mem.eql(u8, result, "error union: 1234\n"));
}
{
var buf1: [32]u8 = undefined;
const value: %i32 = error.InvalidChar;
const result = bufPrint(buf1[0..], "error union: {}\n", value);
assert(mem.eql(u8, result, "error union: error.InvalidChar\n"));
}
}