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// SPDX-License-Identifier: MPL-2.0
// (c) Hare authors <https://harelang.org>
use ascii;
use strings;
use strconv;
use types;
// Tagged union of the [[formattable]] types and [[mods]]. Used for
// functions which accept format strings.
export type field = (...formattable | *mods);
// Tagged union of all types which are formattable.
export type formattable = (...types::numeric | uintptr | str | rune | bool |
nullable *opaque | void);
// Negative modifier. Specifies for numerical arguments when to prepend a plus
// or minus sign or a blank space.
export type neg = enum {
NONE,
SPACE,
PLUS,
};
// Alignment modifier. Specifies how to align an argument within a given width.
export type alignment = enum {
RIGHT,
CENTER,
LEFT,
};
// Specifies how to format an argument.
export type mods = struct {
alignment: alignment,
pad: rune,
neg: neg,
width: size,
prec: size,
base: strconv::base,
ffmt: strconv::ffmt,
fflags: strconv::fflags,
};
type iterator = struct {
iter: strings::iterator,
args: []field,
idx: size,
checkunused: bool,
};
fn iter(fmt: str, args: []field) iterator = iterator {
iter = strings::iter(fmt),
args = args,
idx = 0,
checkunused = true,
};
fn next(it: *iterator) (str | (formattable, mods) | done) = {
let r = match (strings::next(&it.iter)) {
case done =>
return done;
case let r: rune =>
yield r;
};
switch (r) {
case '{' => void; // handled below
case '}' =>
match (strings::next(&it.iter)) {
case done =>
abort("Invalid format string (hanging '}')");
case let r: rune =>
assert(r == '}', "Invalid format string (hanging '}')");
};
return "}";
case =>
strings::prev(&it.iter);
let start = it.iter;
for (let r => strings::next(&it.iter)) {
if (r == '{' || r == '}') {
strings::prev(&it.iter);
break;
};
};
return strings::slice(&start, &it.iter);
};
r = getrune(it);
if (r == '{') {
return "{";
};
let idx = if (ascii::isdigit(r)) {
strings::prev(&it.iter);
it.checkunused = false;
defer r = getrune(it);
yield scan_sz(it);
} else {
defer it.idx += 1;
yield it.idx;
};
assert(idx < len(it.args), "Not enough parameters given");
let arg = it.args[idx] as formattable;
let mod = mods { ... };
switch (r) {
case ':' =>
scan_modifiers(it, &mod);
case '%' =>
r = getrune(it);
let idx = if (ascii::isdigit(r)) {
strings::prev(&it.iter);
it.checkunused = false;
defer r = getrune(it);
yield scan_sz(it);
} else {
defer it.idx += 1;
yield it.idx;
};
assert(idx < len(it.args), "Not enough parameters given");
mod = *(it.args[idx] as *mods);
assert(r == '}', "Invalid format string (didn't find '}' after modifier index)");
case '}' => void;
case => abort("Invalid format string");
};
return (arg, mod);
};
fn scan_modifiers(it: *iterator, mod: *mods) void = {
mod.pad = ' ';
for (true) switch (getrune(it)) {
// alignment
case '-' => mod.alignment = alignment::LEFT;
case '=' => mod.alignment = alignment::CENTER;
// padding
case '_' => mod.pad = getrune(it);
// negation
case ' ' => mod.neg = neg::SPACE;
case '+' => mod.neg = neg::PLUS;
// base
case 'x' => mod.base = strconv::base::HEX_LOWER;
case 'X' => mod.base = strconv::base::HEX_UPPER;
case 'o' => mod.base = strconv::base::OCT;
case 'b' => mod.base = strconv::base::BIN;
// ffmt
case 'e' => mod.ffmt = strconv::ffmt::E;
case 'f' => mod.ffmt = strconv::ffmt::F;
case 'g' => mod.ffmt = strconv::ffmt::G;
// fflags
case 'F' =>
switch (getrune(it)) {
case 's' => mod.fflags |= strconv::fflags::SHOW_POS;
case '.' => mod.fflags |= strconv::fflags::SHOW_POINT;
case 'U' => mod.fflags |= strconv::fflags::UPPERCASE;
case 'E' => mod.fflags |= strconv::fflags::UPPER_EXP;
case 'S' => mod.fflags |= strconv::fflags::SHOW_POS_EXP;
case '2' => mod.fflags |= strconv::fflags::SHOW_TWO_EXP_DIGITS;
case => abort("Invalid float flag");
};
// precision
case '.' => mod.prec = scan_sz(it);
// width
case '1', '2', '3', '4', '5', '6', '7', '8', '9' =>
strings::prev(it);
mod.width = scan_sz(it);
case =>
strings::prev(it);
break;
};
assert(getrune(it) == '}', "Invalid format string (unterminated '{')");
};
fn scan_sz(it: *iterator) size = {
let start = it.iter;
assert(ascii::isdigit(getrune(it)));
for (ascii::isdigit(getrune(it))) void;
strings::prev(&it.iter);
match (strconv::stoz(strings::slice(&start, &it.iter))) {
case strconv::invalid =>
abort("Invalid format string (invalid integer)");
case strconv::overflow =>
abort("Invalid format string (integer overflow)");
case let z: size =>
return z;
};
};
fn getrune(it: *iterator) rune = {
match (strings::next(&it.iter)) {
case done =>
abort("Invalid format string (unterminated '{')");
case let r: rune =>
return r;
};
};
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