109 lines
4.2 KiB
Zig
109 lines
4.2 KiB
Zig
// Zero allocation argument parsing for unix-like systems.
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// Released under the Zero Clause BSD (0BSD) license:
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//
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// Copyright 2023 Isaac Freund
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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const std = @import("std");
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const mem = std.mem;
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pub const Flag = struct {
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name: [:0]const u8,
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kind: enum { boolean, arg },
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};
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pub fn parser(comptime Arg: type, comptime flags: []const Flag) type {
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switch (Arg) {
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// TODO consider allowing []const u8
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[:0]const u8, [*:0]const u8 => {}, // ok
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else => @compileError("invalid argument type: " ++ @typeName(Arg)),
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}
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return struct {
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pub const Result = struct {
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/// Remaining args after the recognized flags
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args: []const Arg,
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/// Data obtained from parsed flags
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flags: Flags,
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pub const Flags = flags_type: {
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var fields: []const std.builtin.Type.StructField = &.{};
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for (flags) |flag| {
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const field: std.builtin.Type.StructField = switch (flag.kind) {
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.boolean => .{
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.name = flag.name,
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.type = bool,
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.default_value = &false,
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.is_comptime = false,
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.alignment = @alignOf(bool),
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},
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.arg => .{
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.name = flag.name,
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.type = ?[:0]const u8,
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.default_value = &@as(?[:0]const u8, null),
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.is_comptime = false,
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.alignment = @alignOf(?[:0]const u8),
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},
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};
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fields = fields ++ [_]std.builtin.Type.StructField{field};
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}
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break :flags_type @Type(.{ .Struct = .{
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.layout = .auto,
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.fields = fields,
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.decls = &.{},
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.is_tuple = false,
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} });
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};
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};
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pub fn parse(args: []const Arg) !Result {
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var result_flags: Result.Flags = .{};
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var i: usize = 0;
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outer: while (i < args.len) : (i += 1) {
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const arg = switch (Arg) {
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[*:0]const u8 => mem.sliceTo(args[i], 0),
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[:0]const u8 => args[i],
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else => unreachable,
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};
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inline for (flags) |flag| {
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if (mem.eql(u8, "-" ++ flag.name, arg)) {
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switch (flag.kind) {
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.boolean => @field(result_flags, flag.name) = true,
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.arg => {
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i += 1;
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if (i == args.len) {
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std.log.err("option '-" ++ flag.name ++
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"' requires an argument but none was provided!", .{});
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return error.MissingFlagArgument;
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}
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@field(result_flags, flag.name) = switch (Arg) {
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[*:0]const u8 => mem.sliceTo(args[i], 0),
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[:0]const u8 => args[i],
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else => unreachable,
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};
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},
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}
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continue :outer;
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}
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}
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break;
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}
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return Result{
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.args = args[i..],
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.flags = result_flags,
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};
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}
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};
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}
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