torque
04722f938e
The bakery bakes the user context type into an object so that it doesn't have to be specified over and over again. This ends up being a nicer way of specifying the CLI parameters, except for the fact that it requires a slightly odd comptime block construct due to `var` not working at the top level for some reason (and `comptime var` also not working).
443 lines
18 KiB
Zig
443 lines
18 KiB
Zig
// Copyright (c) 2022 torque <torque@users.noreply.github.com>
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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, provided that the above
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// copyright notice and this permission notice appear in all copies.
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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// PERFORMANCE OF THIS SOFTWARE.
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const std = @import("std");
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const StructField = std.builtin.Type.StructField;
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pub const meta = @import("./meta.zig");
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pub const params = @import("./params.zig");
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pub const Command = @import("./bakery.zig").Command;
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pub const OptionError = error{
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BadShortOption,
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BadLongOption,
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UnknownOption,
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MissingOption,
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MissingArgument,
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ExtraArguments,
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};
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/// spec is a tuple of Option, Flag, and Argument
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pub fn CommandParser(
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comptime commandData: params.CommandData,
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comptime spec: anytype,
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comptime UserContext: type,
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comptime callback: *const fn (UserContext, CommandResult(spec, UserContext)) anyerror!void,
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) type {
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comptime var argCount = 0;
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comptime for (spec) |param| {
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switch (@TypeOf(param).brand) {
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.Argument => argCount += 1,
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.Option, .Flag, .Command => continue,
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}
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};
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const ResultType = CommandResult(spec, UserContext);
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const RequiredType = RequiredTracker(spec);
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const ParseState = enum { Mixed, ForcedArgs };
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return struct {
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pub const brand: params.Brand = .Command;
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pub const ContextType = UserContext;
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// this should be copied at compile time
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var data: params.CommandData = commandData;
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/// parse command line arguments from an iterator
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pub fn execute(self: @This(), alloc: std.mem.Allocator, comptime argit_type: type, argit: *argit_type, context: UserContext) !void {
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try self.attachSubcommands(alloc);
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var result: ResultType = createCommandresult();
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var required: RequiredType = .{};
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var parseState: ParseState = .Mixed;
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try extractEnvVars(alloc, &result, &required, context);
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var seenArgs: u32 = 0;
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argloop: while (argit.next()) |arg| {
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if (parseState == .Mixed and arg.len > 1 and arg[0] == '-') {
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if (std.mem.eql(u8, "--", arg)) {
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// TODO: the way this works, -- only forces argument
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// parsing until a subcommand is found. This seems
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// reasonable to me, but it may be unexpected that
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// `command -a -- subcommand -b` parses b as an option
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// flag. We could propagate the forced args flag to
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// subcommands, but I'm not sure that would be better.
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//
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// Another option is to stop parsing altogether when --
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// is hit, but that means that subcommands cannot be
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// invoked at the same time as forced arguments, which
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// seems worse somehow, as it affects macroscopic CLI
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// behavior.
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parseState = .ForcedArgs;
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continue :argloop;
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}
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if (arg[1] == '-') {
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// we have a long flag or option
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specloop: inline for (spec) |param| {
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switch (@TypeOf(param).brand) {
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.Option => {
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// have to force lower the handler to runtime
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// var handler = param.handler.?;
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if (param.long) |flag| {
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if (std.mem.eql(u8, flag, arg)) {
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if (comptime param.required()) {
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@field(required, param.name) = true;
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}
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const val = argit.next() orelse return OptionError.MissingArgument;
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if (param.hideResult == false) {
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@field(result, param.name) = try param.handler.?(context, val);
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}
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continue :argloop;
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}
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}
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},
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.Flag => {
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inline for (.{ .{ param.truthy.long, true }, .{ param.falsy.long, false } }) |variant| {
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if (variant[0]) |flag| {
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if (std.mem.eql(u8, flag, arg)) {
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if (param.eager) |handler| {
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try handler(context, data);
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}
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if (param.hideResult == false) {
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@field(result, param.name) = variant[1];
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}
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continue :argloop;
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}
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}
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}
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},
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.Argument, .Command => continue :specloop,
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}
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}
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// nothing matched
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return OptionError.UnknownOption;
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} else {
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// we have a short flag, which may be multiple fused flags
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shortloop: for (arg[1..]) |shorty, idx| {
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specloop: inline for (spec) |param| {
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switch (@TypeOf(param).brand) {
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.Option => {
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// var handler = param.handler.?;
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if (param.short) |flag| {
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if (flag[1] == shorty) {
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if (comptime param.required()) {
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@field(required, param.name) = true;
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}
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const val = if (arg.len > (idx + 2))
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arg[(idx + 2)..]
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else
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argit.next() orelse return OptionError.MissingArgument;
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if (param.hideResult == false) {
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@field(result, param.name) = try param.handler.?(context, val);
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}
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continue :argloop;
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}
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}
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},
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.Flag => {
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inline for (.{ .{ param.truthy.short, true }, .{ param.falsy.short, false } }) |variant| {
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if (variant[0]) |flag| {
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if (flag[1] == shorty) {
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if (param.eager) |handler| {
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try handler(context, data);
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}
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if (param.hideResult == false) {
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@field(result, param.name) = variant[1];
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}
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continue :shortloop;
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}
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}
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}
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},
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.Argument, .Command => continue :specloop,
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}
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}
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// nothing matched
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return OptionError.UnknownOption;
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}
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}
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} else {
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// we have a subcommand or an Argument. Arguments are parsed first, exclusively.
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defer seenArgs += 1;
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comptime var idx = 0;
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inline for (spec) |param| {
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switch (@TypeOf(param).brand) {
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.Command => {
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if (std.mem.eql(u8, @TypeOf(param).data.name, arg)) {
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// we're calling a subcommand
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try checkErrors(seenArgs, required);
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try callback(context, result);
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return param.execute(alloc, argit_type, argit, context);
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}
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},
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.Argument => {
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if (seenArgs == idx) {
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if (comptime param.required()) {
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@field(required, param.name) = true;
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}
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// var handler = param.handler;
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@field(result, param.name) = try param.handler.?(context, arg);
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continue :argloop;
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}
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idx += 1;
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},
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else => continue,
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}
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}
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}
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}
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try checkErrors(seenArgs, required);
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try callback(context, result);
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}
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pub fn OutType() type {
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return CommandResult(spec, UserContext);
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}
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inline fn checkErrors(seenArgs: u32, required: RequiredType) OptionError!void {
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if (seenArgs < argCount) {
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return OptionError.MissingArgument;
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} else if (seenArgs > argCount) {
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return OptionError.ExtraArguments;
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}
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describeError(required);
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inline for (@typeInfo(@TypeOf(required)).Struct.fields) |field| {
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if (@field(required, field.name) == false) {
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return OptionError.MissingOption;
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}
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}
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}
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pub fn describeError(required: RequiredType) void {
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inline for (@typeInfo(@TypeOf(required)).Struct.fields) |field| {
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if (@field(required, field.name) == false) {
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std.debug.print("missing {s}\n", .{field.name});
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}
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}
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}
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fn attachSubcommands(_: @This(), alloc: std.mem.Allocator) !void {
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if (data.subcommands == null) {
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data.subcommands = std.ArrayList(*params.CommandData).init(alloc);
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}
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inline for (spec) |param| {
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switch (@TypeOf(param).brand) {
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.Command => {
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try data.subcommands.?.append(&@TypeOf(param).data);
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},
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else => continue,
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}
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}
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}
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fn scryTruthiness(alloc: std.mem.Allocator, input: []const u8) !bool {
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// empty string is falsy.
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if (input.len == 0) return false;
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if (input.len <= 5) {
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const comp = try std.ascii.allocLowerString(alloc, input);
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defer alloc.free(comp);
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inline for ([_][]const u8{ "false", "no", "0" }) |candidate| {
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if (std.mem.eql(u8, comp, candidate)) {
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return false;
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}
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}
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}
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// TODO: actually try float conversion on input string? This seems
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// really silly to me, in the context of the shell, but for example
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// MY_VAR=0 evaluates to false but MY_VAR=0.0 evaluates to true. And
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// if we accept multiple representations of zero, a whole can of
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// worms gets opened. Should 0x0 be falsy? 0o0? That's a lot of
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// goofy edge cases.
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// any nonempty value is considered to be truthy.
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return true;
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}
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fn extractEnvVars(
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alloc: std.mem.Allocator,
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result: *ResultType,
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required: *RequiredType,
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context: UserContext,
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) !void {
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var env: std.process.EnvMap = try std.process.getEnvMap(alloc);
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defer env.deinit();
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inline for (spec) |param| {
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const ParamType = @TypeOf(param);
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switch (ParamType.brand) {
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.Option => {
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if (param.envVar) |want| {
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if (env.get(want)) |value| {
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if (param.required()) {
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@field(required, param.name) = true;
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}
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@field(result, param.name) = try param.handler.?(context, value);
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}
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}
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},
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.Flag => {
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if (param.envVar) |want| {
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if (env.get(want)) |value| {
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@field(result, param.name) = try scryTruthiness(alloc, value);
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}
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}
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},
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.Argument, .Command => continue,
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}
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}
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}
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inline fn createCommandresult() ResultType {
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var result: ResultType = undefined;
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inline for (spec) |param| {
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switch (@TypeOf(param).brand) {
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.Command => continue,
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else => if (param.hideResult == false) {
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@field(result, param.name) = param.default orelse continue;
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},
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}
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}
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return result;
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}
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};
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}
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pub fn CommandResult(comptime spec: anytype, comptime UserContext: type) type {
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comptime {
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// not sure how to do this without iterating twice, so let's iterate
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// twice
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var outsize = 0;
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for (spec) |param| {
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const ParamType = @TypeOf(param);
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if (ParamType.ContextType != UserContext) {
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@compileError("param \"" ++ param.name ++ "\" has wrong context type (wanted: " ++ @typeName(UserContext) ++ ", got: " ++ @typeName(ParamType.ContextType) ++ ")");
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}
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switch (ParamType.brand) {
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.Argument, .Option => {
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if (param.handler == null) {
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@compileError("param \"" ++ param.name ++ "\" does not have a handler");
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}
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},
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else => {},
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}
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switch (ParamType.brand) {
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.Command => continue,
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else => {
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if (param.hideResult == false) {
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outsize += 1;
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}
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},
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}
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}
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var fields: [outsize]StructField = undefined;
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var idx = 0;
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for (spec) |param| {
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const ParamType = @TypeOf(param);
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switch (ParamType.brand) {
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.Command => continue,
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else => if (param.hideResult == true) continue,
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}
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const FieldType = ParamType.ResultType;
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fields[idx] = .{
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.name = param.name,
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.field_type = FieldType,
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.default_value = @ptrCast(?*const anyopaque, ¶m.default),
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.is_comptime = false,
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.alignment = @alignOf(FieldType),
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};
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idx += 1;
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}
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return @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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fn RequiredTracker(comptime spec: anytype) type {
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comptime {
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// not sure how to do this without iterating twice, so let's iterate
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// twice
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var outsize = 0;
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for (spec) |param| {
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const ParamType = @TypeOf(param);
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switch (ParamType.brand) {
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// flags are always optional, and commands don't map into the
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// output type.
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.Flag, .Command => continue,
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.Argument, .Option => if (param.required()) {
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// if mayBeOptional is false, then the argument/option is
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// required. Otherwise, we have to check if a default has
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// been provided.
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outsize += 1;
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},
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}
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}
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var fields: [outsize]StructField = undefined;
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var idx = 0;
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for (spec) |param| {
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const ParamType = @TypeOf(param);
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switch (ParamType.brand) {
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.Flag, .Command => continue,
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.Argument, .Option => if (param.required()) {
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fields[idx] = .{
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.name = param.name,
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.field_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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idx += 1;
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},
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}
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}
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return @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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test {
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_ = meta;
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}
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