1 files changed, 317 insertions, 0 deletions

diff --git a/index.zig b/index.zig
new file mode 100644
index 0000000..7b82211
--- /dev/null
+++ b/index.zig
@@ -0,0 +1,317 @@
+pub const core = @import("core.zig");
+
+const builtin = @import("builtin");
+const std     = @import("std");
+
+const mem   = std.mem;
+const fmt   = std.fmt;
+const debug = std.debug;
+const io    = std.io;
+
+const assert = debug.assert;
+
+pub const Param = struct {
+    field: []const u8,
+    short: ?u8,
+    long: ?[]const u8,
+    takes_value: ?Parser,
+    required: bool,
+    position: ?usize,
+
+    pub fn short(s: u8) Param {
+        return Param{
+            .field = []u8{s},
+            .short = s,
+            .long = null,
+            .takes_value = null,
+            .required = false,
+            .position = null,
+        };
+    }
+
+    pub fn long(l: []const u8) Param {
+        return Param{
+            .field = l,
+            .short = null,
+            .long = l,
+            .takes_value = null,
+            .required = false,
+            .position = null,
+        };
+    }
+
+    pub fn value(f: []const u8) Param {
+        return Param{
+            .field = f,
+            .short = null,
+            .long = null,
+            .takes_value = null,
+            .required = false,
+            .position = null,
+        };
+    }
+
+    /// Initialize a ::Param.
+    /// If ::name.len == 0, then it's a value parameter: "value".
+    /// If ::name.len == 1, then it's a short parameter: "-s".
+    /// If ::name.len > 1, then it's a long parameter: "--long".
+    pub fn smart(name: []const u8) Param {
+        return Param{
+            .field = name,
+            .short = if (name.len == 1) name[0] else null,
+            .long = if (name.len > 1) name else null,
+            .takes_value = null,
+            .required = false,
+            .position = null,
+        };
+    }
+
+    pub fn with(param: &const Param, comptime field_name: []const u8, v: var) Param {
+        var res = *param;
+        @field(res, field_name) = v;
+        return res;
+    }
+};
+
+pub fn Clap(comptime Result: type) type {
+    return struct {
+        const Self = this;
+
+        defaults: Result,
+        params: []const Param,
+
+        pub fn parse(comptime clap: &const Self, allocator: &mem.Allocator, arg_iter: &core.ArgIterator) !Result {
+            var result = clap.defaults;
+            const core_params = comptime blk: {
+                var res: [clap.params.len]core.Param(usize) = undefined;
+
+                for (clap.params) |p, i| {
+                    res[i] = core.Param(usize) {
+                        .id = i,
+                        .command = null,
+                        .short = p.short,
+                        .long = p.long,
+                        .takes_value = p.takes_value != null,
+                    };
+                }
+
+                break :blk res;
+            };
+
+            var handled = comptime blk: {
+                var res: [clap.params.len]bool = undefined;
+                for (clap.params) |p, i| {
+                    res[i] = !p.required;
+                }
+
+                break :blk res;
+            };
+
+            var pos: usize = 0;
+            var iter = core.Iterator(usize).init(core_params, arg_iter, allocator);
+            defer iter.deinit();
+            while (try iter.next()) |arg| : (pos += 1) {
+                inline for(clap.params) |param, i| {
+                    if (arg.id == i) {
+                        if (param.position) |expected| {
+                            if (expected != pos)
+                                return error.InvalidPosition;
+                        }
+
+                        if (param.takes_value) |parser| {
+                            try parser.parse(&@field(result, param.field), ??arg.value);
+                        } else {
+                            @field(result, param.field) = true;
+                        }
+                        handled[i] = true;
+                    }
+                }
+            }
+
+            return result;
+        }
+    };
+}
+
+pub const Parser = struct {
+    const UnsafeFunction = &const void;
+
+    FieldType: type,
+    Errors: type,
+    func: UnsafeFunction,
+
+    pub fn init(comptime FieldType: type, comptime Errors: type, func: parseFunc(FieldType, Errors)) Parser {
+        return Parser {
+            .FieldType = FieldType,
+            .Errors = Errors,
+            .func = @ptrCast(UnsafeFunction, func),
+        };
+    }
+
+    fn parse(comptime parser: Parser, field_ptr: takePtr(parser.FieldType), arg: []const u8) parser.Errors!void {
+        return @ptrCast(parseFunc(parser.FieldType, parser.Errors), parser.func)(field_ptr, arg);
+    }
+
+    // TODO: This is a workaround, since we don't have pointer reform yet.
+    fn takePtr(comptime T: type) type { return &T; }
+
+    fn parseFunc(comptime FieldType: type, comptime Errors: type) type {
+        return fn(&FieldType, []const u8) Errors!void;
+    }
+
+    pub fn int(comptime Int: type, comptime radix: u8) Parser {
+        const func = struct {
+            fn i(field_ptr: &Int, arg: []const u8) !void {
+                *field_ptr = try fmt.parseInt(Int, arg, radix);
+            }
+        }.i;
+        return Parser.init(
+            Int,
+            @typeOf(func).ReturnType.ErrorSet,
+            func
+        );
+    }
+
+    const string = Parser.init(
+        []const u8,
+        error{},
+        struct {
+            fn s(field_ptr: &[]const u8, arg: []const u8) (error{}!void) {
+                *field_ptr = arg;
+            }
+        }.s
+    );
+};
+
+
+const Options = struct {
+    str: []const u8,
+    int: i64,
+    uint: u64,
+    a: bool,
+    b: bool,
+    cc: bool,
+
+    pub fn with(op: &const Options, comptime field: []const u8, value: var) Options {
+        var res = *op;
+        @field(res, field) = value;
+        return res;
+    }
+};
+
+const default = Options {
+    .str = "",
+    .int = 0,
+    .uint = 0,
+    .a = false,
+    .b = false,
+    .cc = false,
+};
+
+fn testNoErr(comptime clap: &const Clap(Options), args: []const []const u8, expected: &const Options) void {
+    var arg_iter = core.ArgSliceIterator.init(args);
+    const actual = clap.parse(debug.global_allocator, &arg_iter.iter) catch unreachable;
+    assert(mem.eql(u8, expected.str, actual.str));
+    assert(expected.int == actual.int);
+    assert(expected.uint == actual.uint);
+    assert(expected.a == actual.a);
+    assert(expected.b == actual.b);
+    assert(expected.cc == actual.cc);
+}
+
+fn testErr(comptime clap: &const Clap(Options), args: []const []const u8, expected: error) void {
+    var arg_iter = core.ArgSliceIterator.init(args);
+    if (clap.parse(debug.global_allocator, &arg_iter.iter)) |actual| {
+        unreachable;
+    } else |err| {
+        assert(err == expected);
+    }
+}
+
+test "clap.core" {
+    _ = core;
+}
+
+test "clap: short" {
+    const clap = comptime Clap(Options) {
+        .defaults = default,
+        .params = []Param {
+            Param.smart("a"),
+            Param.smart("b"),
+            Param.smart("int")
+                .with("short", 'i')
+                .with("takes_value", Parser.int(i64, 10))
+        }
+    };
+
+    testNoErr(clap, [][]const u8 { "-a" },       default.with("a", true));
+    testNoErr(clap, [][]const u8 { "-a", "-b" }, default.with("a", true).with("b",  true));
+    testNoErr(clap, [][]const u8 { "-i=100" },   default.with("int", 100));
+    testNoErr(clap, [][]const u8 { "-i100" },   default.with("int", 100));
+    testNoErr(clap, [][]const u8 { "-i", "100" },   default.with("int", 100));
+    testNoErr(clap, [][]const u8 { "-ab" },      default.with("a", true).with("b",  true));
+    testNoErr(clap, [][]const u8 { "-abi", "100" }, default.with("a", true).with("b", true).with("int",  100));
+    testNoErr(clap, [][]const u8 { "-abi=100" }, default.with("a", true).with("b", true).with("int",  100));
+    testNoErr(clap, [][]const u8 { "-abi100" }, default.with("a", true).with("b", true).with("int",  100));
+}
+
+test "clap: long" {
+    const clap = comptime Clap(Options) {
+        .defaults = default,
+        .params = []Param {
+            Param.smart("cc"),
+            Param.smart("int").with("takes_value", Parser.int(i64, 10)),
+            Param.smart("uint").with("takes_value", Parser.int(u64, 10)),
+            Param.smart("str").with("takes_value", Parser.string),
+        }
+    };
+
+    testNoErr(clap, [][]const u8 { "--cc" },         default.with("cc",  true));
+    testNoErr(clap, [][]const u8 { "--int", "100" }, default.with("int",  100));
+}
+
+test "clap: value bool" {
+    const clap = comptime Clap(Options) {
+        .defaults = default,
+        .params = []Param {
+            Param.smart("a"),
+        }
+    };
+
+    testNoErr(clap, [][]const u8 { "-a" }, default.with("a",  true));
+}
+
+test "clap: value str" {
+    const clap = comptime Clap(Options) {
+        .defaults = default,
+        .params = []Param {
+            Param.smart("str").with("takes_value", Parser.string),
+        }
+    };
+
+    testNoErr(clap, [][]const u8 { "--str", "Hello World!" }, default.with("str", "Hello World!"));
+}
+
+test "clap: value int" {
+    const clap = comptime Clap(Options) {
+        .defaults = default,
+        .params = []Param {
+            Param.smart("int").with("takes_value", Parser.int(i64, 10)),
+        }
+    };
+
+    testNoErr(clap, [][]const u8 { "--int", "100" }, default.with("int", 100));
+}
+
+test "clap: position" {
+    const clap = comptime Clap(Options) {
+        .defaults = default,
+        .params = []Param {
+            Param.smart("a").with("position", 0),
+            Param.smart("b").with("position", 1),
+        }
+    };
+
+    testNoErr(clap, [][]const u8 { "-a", "-b" }, default.with("a", true).with("b", true));
+    testErr(clap, [][]const u8 { "-b", "-a" }, error.InvalidPosition);
+}