Add package core:flags

core/flags/parsing.odin

@@ -0,0 +1,94 @@
+package flags
+
+import "core:container/bit_array"
+
+Parsing_Style :: enum {
+	// Odin-style: `-flag`, `-flag:option`, `-map:key=value`
+	Odin,
+	// UNIX-style: `-flag` or `--flag`, `--flag=argument`, `--flag argument repeating-argument`
+	Unix,
+}
+
+/*
+Parse a slice of command-line arguments into an annotated struct.
+
+*Allocates Using Provided Allocator*
+
+By default, this proc will only allocate memory outside of its lifetime if it
+has to append to a dynamic array, set a map value, or set a cstring.
+
+The program is expected to free any allocations on `model` as a result of parsing.
+
+Inputs:
+- model: A pointer to an annotated struct with flag definitions.
+- args: A slice of strings, usually `os.args[1:]`.
+- style: The argument parsing style.
+- validate_args: If `true`, will ensure that all required arguments are set if no errors occurred.
+- strict: If `true`, will return on first error. Otherwise, parsing continues.
+- allocator: (default: context.allocator)
+- loc: The caller location for debugging purposes (default: #caller_location)
+
+Returns:
+- error: A union of errors; parsing, file open, a help request, or validation.
+*/
+@(optimization_mode="size")
+parse :: proc(
+	model: ^$T,
+	args: []string,
+	style: Parsing_Style = .Odin,
+	validate_args: bool = true,
+	strict: bool = true,
+	allocator := context.allocator,
+	loc := #caller_location,
+) -> (error: Error) {
+	context.allocator = allocator
+	validate_structure(model^, style, loc)
+
+	parser: Parser
+	defer {
+		bit_array.destroy(&parser.filled_pos)
+		bit_array.destroy(&parser.fields_set)
+	}
+
+	switch style {
+	case .Odin:
+		for arg in args {
+			error = parse_one_odin_arg(model, &parser, arg)
+			if strict && error != nil {
+				return
+			}
+		}
+
+	case .Unix:
+		// Support for `-flag argument (repeating-argument ...)`
+		future_args: int
+		current_flag: string
+
+		for i := 0; i < len(args); i += 1 {
+			#no_bounds_check arg := args[i]
+			future_args, current_flag, error = parse_one_unix_arg(model, &parser, arg)
+			if strict && error != nil {
+				return
+			}
+
+			for /**/; future_args > 0; future_args -= 1 {
+				i += 1
+				if i == len(args) {
+					break
+				}
+				#no_bounds_check arg = args[i]
+
+				error = set_option(model, &parser, current_flag, arg)
+				if strict && error != nil {
+					return
+				}
+			}
+		}
+	}
+
+	if error == nil && validate_args {
+		return validate_arguments(model, &parser)
+	}
+
+	return
+}