490 lines
14 KiB
Elixir
490 lines
14 KiB
Elixir
defmodule OptionParser do
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@moduledoc """
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This module contains functions to parse command line options.
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"""
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@type argv :: [String.t]
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@type parsed :: Keyword.t
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@type errors :: [{String.t, String.t | nil}]
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@type options :: [switches: Keyword.t, strict: Keyword.t, aliases: Keyword.t]
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@doc """
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Parses `argv` into a keywords list.
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It returns the parsed values, remaining arguments and the
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invalid options.
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## Examples
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iex> OptionParser.parse(["--debug"])
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{[debug: true], [], []}
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iex> OptionParser.parse(["--source", "lib"])
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{[source: "lib"], [], []}
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iex> OptionParser.parse(["--source-path", "lib", "test/enum_test.exs", "--verbose"])
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{[source_path: "lib", verbose: true], ["test/enum_test.exs"], []}
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By default, Elixir will try to automatically parse switches.
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Switches without an argument, like `--debug` will automatically
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be set to `true`. Switches followed by a value will be assigned
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to the value, always as strings.
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Note Elixir also converts the switches to underscore atoms, as
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`--source-path` becomes `:source_path`, to better suit Elixir
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conventions. This means that option names on the command line cannot contain
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underscores; such options will be reported as `:undefined` (in strict mode)
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or `:invalid` (in basic mode).
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## Switches
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Many times though, it is better to explicitly list the available
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switches and their formats. The switches can be specified via two
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different options:
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* `:strict` - the switches are strict. Any switch that does not
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exist in the switch list is treated as an error.
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* `:switches` - defines some switches. Switches that does not
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exist in the switch list are still attempted to be parsed.
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Note only `:strict` or `:switches` may be given at once.
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For each switch, the following types are supported:
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* `:boolean` - marks the given switch as a boolean. Boolean switches
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never consume the following value unless it is `true` or
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`false`.
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* `:integer` - parses the switch as an integer.
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* `:float` - parses the switch as a float.
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* `:string` - returns the switch as a string.
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If a switch can't be parsed or is not specified in the strict case,
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the option is returned in the invalid options list (third element
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of the returned tuple).
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The following extra "types" are supported:
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* `:keep` - keeps duplicated items in the list instead of overriding
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Examples:
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iex> OptionParser.parse(["--unlock", "path/to/file"], strict: [unlock: :boolean])
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{[unlock: true], ["path/to/file"], []}
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iex> OptionParser.parse(["--unlock", "--limit", "0", "path/to/file"],
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...> strict: [unlock: :boolean, limit: :integer])
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{[unlock: true, limit: 0], ["path/to/file"], []}
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iex> OptionParser.parse(["--limit", "3"], strict: [limit: :integer])
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{[limit: 3], [], []}
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iex> OptionParser.parse(["--limit", "xyz"], strict: [limit: :integer])
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{[], [], [{"--limit", "xyz"}]}
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iex> OptionParser.parse(["--unknown", "xyz"], strict: [])
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{[], ["xyz"], [{"--unknown", nil}]}
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iex> OptionParser.parse(["--limit", "3", "--unknown", "xyz"],
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...> switches: [limit: :integer])
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{[limit: 3, unknown: "xyz"], [], []}
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iex> OptionParser.parse(["--unlock", "path/to/file", "--unlock", "path/to/another/file"], strict: [unlock: :keep])
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{[unlock: "path/to/file", unlock: "path/to/another/file"], [], []}
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## Negation switches
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In case a switch is declared as boolean, it may be passed as `--no-SWITCH`
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which will set the option to `false`:
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iex> OptionParser.parse(["--no-op", "path/to/file"], switches: [op: :boolean])
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{[op: false], ["path/to/file"], []}
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## Aliases
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A set of aliases can be given as options too:
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iex> OptionParser.parse(["-d"], aliases: [d: :debug])
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{[debug: true], [], []}
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"""
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@spec parse(argv, options) :: {parsed, argv, errors}
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def parse(argv, opts \\ []) when is_list(argv) and is_list(opts) do
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do_parse(argv, compile_config(opts), [], [], [], true)
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end
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@doc """
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Similar to `parse/2` but only parses the head of `argv`;
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as soon as it finds a non-switch, it stops parsing.
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See `parse/2` for more information.
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## Example
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iex> OptionParser.parse_head(["--source", "lib", "test/enum_test.exs", "--verbose"])
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{[source: "lib"], ["test/enum_test.exs", "--verbose"], []}
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iex> OptionParser.parse_head(["--verbose", "--source", "lib", "test/enum_test.exs", "--unlock"])
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{[verbose: true, source: "lib"], ["test/enum_test.exs", "--unlock"], []}
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"""
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@spec parse_head(argv, options) :: {parsed, argv, errors}
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def parse_head(argv, opts \\ []) when is_list(argv) and is_list(opts) do
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do_parse(argv, compile_config(opts), [], [], [], false)
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end
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defp do_parse([], _config, opts, args, invalid, _all?) do
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{Enum.reverse(opts), Enum.reverse(args), Enum.reverse(invalid)}
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end
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defp do_parse(argv, {aliases, switches, strict}=config, opts, args, invalid, all?) do
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case next(argv, aliases, switches, strict) do
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{:ok, option, value, rest} ->
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# the option exist and it was successfully parsed
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kinds = List.wrap Keyword.get(switches, option)
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new_opts = do_store_option(opts, option, value, kinds)
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do_parse(rest, config, new_opts, args, invalid, all?)
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{:invalid, option, value, rest} ->
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# the option exist but it has wrong value
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do_parse(rest, config, opts, args, [{option, value}|invalid], all?)
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{:undefined, option, _value, rest} ->
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# the option does not exist (for strict cases)
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do_parse(rest, config, opts, args, [{option, nil}|invalid], all?)
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{:error, ["--"|rest]} ->
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{Enum.reverse(opts), Enum.reverse(args, rest), Enum.reverse(invalid)}
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{:error, [arg|rest]=remaining_args} ->
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# there is no option
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if all? do
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do_parse(rest, config, opts, [arg|args], invalid, all?)
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else
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{Enum.reverse(opts), Enum.reverse(args, remaining_args), Enum.reverse(invalid)}
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end
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end
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end
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@doc """
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Low-level function that parses one option.
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It accepts the same options as `parse/2` and `parse_head/2`
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as both functions are built on top of next. This function
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may return:
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* `{:ok, key, value, rest}` - the option `key` with `value` was
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successfully parsed
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* `{:invalid, key, value, rest}` - the option `key` is invalid with `value`
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(returned when the switch type does not match the one given via the
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command line)
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* `{:undefined, key, value, rest}` - the option `key` is undefined
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(returned on strict cases and the switch is unknown)
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* `{:error, rest}` - there are no switches at the top of the given argv
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"""
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@spec next(argv, options) ::
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{:ok, key :: atom, value :: term, argv} |
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{:invalid, String.t, String.t | nil, argv} |
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{:undefined, String.t, String.t | nil, argv} |
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{:error, argv}
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def next(argv, opts \\ []) when is_list(argv) and is_list(opts) do
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{aliases, switches, strict} = compile_config(opts)
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next(argv, aliases, switches, strict)
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end
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defp next([], _aliases, _switches, _strict) do
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{:error, []}
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end
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defp next(["--"|_]=argv, _aliases, _switches, _strict) do
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{:error, argv}
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end
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defp next(["-"|_]=argv, _aliases, _switches, _strict) do
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{:error, argv}
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end
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defp next(["- " <> _|_]=argv, _aliases, _switches, _strict) do
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{:error, argv}
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end
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defp next(["-" <> option|rest], aliases, switches, strict) do
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{option, value} = split_option(option)
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opt_name_bin = "-" <> option
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tagged = tag_option(option, switches, aliases)
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if strict and not option_defined?(tagged, switches) do
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{:undefined, opt_name_bin, value, rest}
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else
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{opt_name, kinds, value} = normalize_option(tagged, value, switches)
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{value, kinds, rest} = normalize_value(value, kinds, rest, strict)
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case validate_option(value, kinds) do
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{:ok, new_value} -> {:ok, opt_name, new_value, rest}
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:invalid -> {:invalid, opt_name_bin, value, rest}
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end
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end
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end
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defp next(argv, _aliases, _switches, _strict) do
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{:error, argv}
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end
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@doc """
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Receives a key-value enumerable and convert it to argv.
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Keys must be atoms. Keys with nil value are discarded,
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boolean values are converted to `--key` or `--no-key`
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and all other values are converted using `to_string/1`.
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## Examples
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iex> OptionParser.to_argv([foo_bar: "baz"])
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["--foo-bar", "baz"]
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iex> OptionParser.to_argv([bool: true, bool: false, discarded: nil])
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["--bool", "--no-bool"]
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"""
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@spec to_argv(Enumerable.t) :: argv
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def to_argv(enum) do
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Enum.flat_map(enum, fn
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{_key, nil} -> []
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{key, true} -> [to_switch(key)]
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{key, false} -> [to_switch(key, "--no-")]
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{key, value} -> [to_switch(key), to_string(value)]
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end)
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end
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defp to_switch(key, prefix \\ "--") when is_atom(key) do
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prefix <> String.replace(Atom.to_string(key), "_", "-")
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end
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@doc ~S"""
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Splits a string into argv chunks.
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## Examples
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iex> OptionParser.split("foo bar")
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["foo", "bar"]
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iex> OptionParser.split("foo \"bar baz\"")
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["foo", "bar baz"]
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"""
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@spec split(String.t) :: argv
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def split(string) do
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do_split(strip_leading_spaces(string), "", [], nil)
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end
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# If we have an escaped quote, simply remove the escape
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defp do_split(<<?\\, quote, t :: binary>>, buffer, acc, quote),
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do: do_split(t, <<buffer::binary, quote>>, acc, quote)
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# If we have a quote and we were not in a quote, start one
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defp do_split(<<quote, t :: binary>>, buffer, acc, nil) when quote in [?", ?'],
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do: do_split(t, buffer, acc, quote)
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# If we have a quote and we were inside it, close it
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defp do_split(<<quote, t :: binary>>, buffer, acc, quote),
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do: do_split(t, buffer, acc, nil)
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# If we have an escaped quote/space, simply remove the escape as long as we are not inside a quote
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defp do_split(<<?\\, h, t :: binary>>, buffer, acc, nil) when h in [?\s, ?', ?"],
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do: do_split(t, <<buffer::binary, h>>, acc, nil)
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# If we have space and we are outside of a quote, start new segment
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defp do_split(<<?\s, t :: binary>>, buffer, acc, nil),
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do: do_split(strip_leading_spaces(t), "", [buffer|acc], nil)
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# All other characters are moved to buffer
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defp do_split(<<h, t::binary>>, buffer, acc, quote) do
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do_split(t, <<buffer::binary, h>>, acc, quote)
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end
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# Finish the string expecting a nil marker
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defp do_split(<<>>, "", acc, nil),
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do: Enum.reverse(acc)
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defp do_split(<<>>, buffer, acc, nil),
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do: Enum.reverse([buffer|acc])
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# Otherwise raise
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defp do_split(<<>>, _, _acc, marker) do
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raise "argv string did not terminate properly, a #{<<marker>>} was opened but never closed"
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end
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defp strip_leading_spaces(" " <> t), do: strip_leading_spaces(t)
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defp strip_leading_spaces(t), do: t
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## Helpers
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defp compile_config(opts) do
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aliases = opts[:aliases] || []
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{switches, strict} = cond do
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s = opts[:switches] ->
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{s, false}
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s = opts[:strict] ->
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{s, true}
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true ->
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{[], false}
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end
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{aliases, switches, strict}
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end
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defp validate_option(value, kinds) do
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{is_invalid, value} = cond do
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:invalid in kinds ->
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{true, value}
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:boolean in kinds ->
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case value do
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t when t in [true, "true"] -> {nil, true}
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f when f in [false, "false"] -> {nil, false}
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_ -> {true, value}
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end
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:integer in kinds ->
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case Integer.parse(value) do
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{value, ""} -> {nil, value}
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_ -> {true, value}
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end
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:float in kinds ->
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case Float.parse(value) do
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{value, ""} -> {nil, value}
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_ -> {true, value}
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end
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true ->
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{nil, value}
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end
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if is_invalid do
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:invalid
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else
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{:ok, value}
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end
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end
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defp do_store_option(dict, option, value, kinds) do
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cond do
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:keep in kinds ->
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[{option, value}|dict]
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true ->
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[{option, value}|Keyword.delete(dict, option)]
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end
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end
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defp tag_option(<<?-, option :: binary>>, switches, _aliases) do
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get_negated(option, switches)
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end
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defp tag_option(option, _switches, aliases) when is_binary(option) do
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opt = get_option(option)
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if alias = aliases[opt] do
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{:default, alias}
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else
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:unknown
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end
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end
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defp option_defined?(:unknown, _switches) do
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false
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end
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defp option_defined?({:negated, option}, switches) do
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Keyword.has_key?(switches, option)
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end
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defp option_defined?({:default, option}, switches) do
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Keyword.has_key?(switches, option)
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end
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defp normalize_option(:unknown, value, _switches) do
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{nil, [:invalid], value}
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end
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defp normalize_option({:negated, option}, value, switches) do
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if value do
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{option, [:invalid], value}
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else
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{option, List.wrap(switches[option]), false}
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end
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end
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defp normalize_option({:default, option}, value, switches) do
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{option, List.wrap(switches[option]), value}
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end
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defp normalize_value(nil, kinds, t, strict) do
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nil_or_true = if strict, do: nil, else: true
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cond do
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:boolean in kinds ->
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{true, kinds, t}
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value_in_tail?(t) ->
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[h|t] = t
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{h, kinds, t}
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kinds == [] ->
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{nil_or_true, kinds, t}
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true ->
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{nil, [:invalid], t}
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end
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end
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defp normalize_value(value, kinds, t, _) do
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{value, kinds, t}
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end
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defp value_in_tail?(["-"|_]), do: true
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defp value_in_tail?(["- " <> _|_]), do: true
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defp value_in_tail?(["-" <> _|_]), do: false
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defp value_in_tail?([]), do: false
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defp value_in_tail?(_), do: true
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defp split_option(option) do
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case :binary.split(option, "=") do
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[h] -> {h, nil}
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[h, t] -> {h, t}
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end
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end
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defp to_underscore(option), do: to_underscore(option, <<>>)
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defp to_underscore("_" <> _rest, _acc), do: nil
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defp to_underscore("-" <> rest, acc),
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do: to_underscore(rest, acc <> "_")
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defp to_underscore(<<c>> <> rest, acc),
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do: to_underscore(rest, <<acc::binary, c>>)
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defp to_underscore(<<>>, acc), do: acc
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defp get_option(option) do
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if str = to_underscore(option) do
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String.to_atom(str)
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end
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end
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defp get_negated("no-" <> rest = original, switches) do
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cond do
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(negated = get_option(rest)) && :boolean in List.wrap(switches[negated]) ->
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{:negated, negated}
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option = get_option(original) ->
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{:default, option}
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true ->
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:unknown
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end
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end
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defp get_negated(rest, _switches) do
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if option = get_option(rest) do
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{:default, option}
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else
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:unknown
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end
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end
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end
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