Add package core:flags

core/flags/internal_parsing.odin

@@ -0,0 +1,162 @@
+//+private
+package flags
+
+import "core:container/bit_array"
+import "core:strconv"
+import "core:strings"
+
+// Used to group state together.
+Parser :: struct {
+	// `fields_set` tracks which arguments have been set.
+	// It uses their struct field index.
+	fields_set: bit_array.Bit_Array,
+
+	// `filled_pos` tracks which arguments have been filled into positional
+	// spots, much like how `fmt` treats them.
+	filled_pos: bit_array.Bit_Array,
+}
+
+parse_one_odin_arg :: proc(model: ^$T, parser: ^Parser, arg: string) -> (error: Error) {
+	arg := arg
+
+	if strings.has_prefix(arg, "-") {
+		arg = arg[1:]
+
+		flag: string
+		assignment_rune: rune
+		find_assignment: for r, i in arg {
+			switch r {
+			case ':', '=':
+				assignment_rune = r
+				flag = arg[:i]
+				arg = arg[1 + i:]
+				break find_assignment
+			case:
+				continue find_assignment
+			}
+		}
+
+		if assignment_rune == 0 {
+			if len(arg) == 0 {
+				return Parse_Error {
+					.No_Flag,
+					"No flag was given.",
+				}
+			}
+
+			// -flag
+			set_odin_flag(model, parser, arg) or_return
+
+		} else if assignment_rune == ':' {
+			// -flag:option <OR> -map:key=value
+			error = set_option(model, parser, flag, arg)
+
+			if error != nil {
+				// -flag:option did not work, so this may be a -map:key=value set.
+				find_equals: for r, i in arg {
+					if r == '=' {
+						key := arg[:i]
+						arg = arg[1 + i:]
+						error = set_key_value(model, parser, flag, key, arg)
+						break find_equals
+					}
+				}
+			}
+
+		} else {
+			// -flag=option, alternative syntax
+			set_option(model, parser, flag, arg) or_return
+		}
+
+	} else {
+		// positional
+		error = push_positional(model, parser, arg)
+	}
+
+	return
+}
+
+parse_one_unix_arg :: proc(model: ^$T, parser: ^Parser, arg: string) -> (
+	future_args: int,
+	current_flag: string,
+	error: Error,
+) {
+	arg := arg
+
+	if strings.has_prefix(arg, "-") {
+		// -flag
+		arg = arg[1:]
+
+		if strings.has_prefix(arg, "-") {
+			// Allow `--` to function as `-`.
+			arg = arg[1:]
+		}
+
+		flag: string
+		find_assignment: for r, i in arg {
+			if r == '=' {
+				// --flag=option
+				flag = arg[:i]
+				arg = arg[1 + i:]
+				error = set_option(model, parser, flag, arg)
+				return
+			}
+		}
+
+		// --flag option, potentially
+		future_args = set_unix_flag(model, parser, arg) or_return
+		current_flag = arg
+
+	} else {
+		// positional
+		error = push_positional(model, parser, arg)
+	}
+
+	return
+}
+
+// Parse a number of requirements specifier.
+//
+// Examples:
+//
+//    `min`
+//    `<max`
+//    `min<max`
+parse_requirements :: proc(str: string) -> (minimum, maximum: int, ok: bool) {
+	if len(str) == 0 {
+		return 1, max(int), true
+	}
+
+	if less_than := strings.index_byte(str, '<'); less_than != -1 {
+		if len(str) == 1 {
+			return 0, 0, false
+		}
+
+		#no_bounds_check left  := str[:less_than]
+		#no_bounds_check right := str[1 + less_than:]
+
+		if left_value, parse_ok := strconv.parse_u64_of_base(left, 10); parse_ok {
+			minimum = cast(int)left_value
+		} else if len(left) > 0 {
+			return 0, 0, false
+		}
+
+		if right_value, parse_ok := strconv.parse_u64_of_base(right, 10); parse_ok {
+			maximum = cast(int)right_value
+		} else if len(right) > 0 {
+			return 0, 0, false
+		} else {
+			maximum = max(int)
+		}
+	} else {
+		if value, parse_ok := strconv.parse_u64_of_base(str, 10); parse_ok {
+			minimum = cast(int)value
+			maximum = max(int)
+		} else {
+			return 0, 0, false
+		}
+	}
+
+	ok = true
+	return
+}