Class: ArgParser::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/arg-parser/parser.rb

Overview

Parser for parsing a command-line

Defined Under Namespace

Classes: EmptyArgs

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(definition = nil) ⇒ Parser

Instantiates a new command-line parser, with the specified command- line definition. A Parser instance delegates unknown methods to the Definition, so its possible to work only with a Parser instance to both define and parse a command-line.

Parameters:

  • definition (Definition) (defaults to: nil) —

    A Definition object that defines the possible arguments that may appear in a command-line. If no definition is supplied, an empty definition is created.



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# File 'lib/arg-parser/parser.rb', line 37

def initialize(definition = nil)
    @definition = definition || Definition.new
    @errors = []
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(mthd, *args) ⇒ Object

Delegate unknown methods to the associated argument Definition object.



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# File 'lib/arg-parser/parser.rb', line 80

def method_missing(mthd, *args)
    if @definition.respond_to?(mthd)
        @definition.send(mthd, *args)
    else
        super
    end
end

Instance Attribute Details

#definition ⇒ Definition (readonly)

Returns The supported Arguments to be used when parsing the command-line.

Returns:

  • (Definition) —

    The supported Arguments to be used when parsing the command-line.



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# File 'lib/arg-parser/parser.rb', line 13

def definition
  @definition
end

#errors ⇒ Array (readonly)

Returns An Array of error message Strings generated during parsing.

Returns:

  • (Array) —

    An Array of error message Strings generated during parsing.



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# File 'lib/arg-parser/parser.rb', line 16

def errors
  @errors
end

Instance Method Details

#classify_tokens(tokens) ⇒ Object

Evaluate the list of values in tokens, and classify them as either keyword/value pairs, or positional arguments. Ideally this would be done without any reference to the defined arguments, but unfortunately there are a couple of issues that require context to be able to handle properly:

  • a keyword arg cannot be distinguished from a flag arg followed by a positional arg without the context of what arguments are expected.

  • command arguments will normally have their own set of additional arguments that must be added once we know which command has been entered.



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# File 'lib/arg-parser/parser.rb', line 99

def classify_tokens(tokens)
    if tokens.is_a?(String)
        require 'csv'
        tokens = CSV.parse(tokens, col_sep: ' ').first
    end
    tokens = [] unless tokens
    pos_vals = []
    kw_vals = {}
    rest_vals = []

    arg = nil
    pos_args = @definition.positional_args
    tokens.each_with_index do |token, i|
        if token.downcase == 'help' && i == 0
            # Accept 'help' as the first token
            @show_help = true
            next
        end
        case token
        when '/?', '-?', '--help'
            @show_help = true
        when /^[-\/]([a-z0-9]+)$/i
            # One or more short keys
            $1.to_s.each_char do |sk|
                kw_vals[arg] = nil if arg
                arg = @definition[sk]
                if FlagArgument === arg
                    kw_vals[arg] = true
                    arg = nil
                elsif PositionalArgument == arg
                    pos_args.delete(arg)
                end
            end
        when /^--(no[nt]?-)?(.+)/i
            # Long key
            kw_vals[arg] = nil if arg
            arg = @definition[$2]
            if FlagArgument === arg || (KeywordArgument === arg && $1)
                kw_vals[arg] = $1 ? false : true
                arg = nil
            elsif PositionalArgument === arg
                pos_args.delete(arg)
            end
        when '--'
            # All subsequent values are rest args
            kw_vals[arg] = nil if arg
            unless rest_vals.empty?
                self.errors << "Too many positional arguments supplied before -- token"
            end
            rest_vals = tokens[(i + 1)..-1]
            break
        else
            if arg
                kw_vals[arg] = token
            elsif pos_args.size > 0
                arg = pos_args.shift
                if CommandArgument === arg
                    if cmd_inst = arg[token]
                        # Merge command's arg set with the current definition
                        @definition = @definition.collapse(cmd_inst)
                        # Insert command positional arguments
                        pos_args.insert(0, *cmd_inst.argument_scope.positional_args)
                        pos_vals << cmd_inst.command_value
                    else
                        self.errors << "'#{token}' is not a valid value for #{arg}; valid values are: #{
                            arg.commands.keys.join(', ')}"
                    end
                    arg = nil   # Commands can't be sensitive
                else
                    pos_vals << token
                end
            else
                rest_vals << token
            end
            tokens[i] = '******' if arg && arg.sensitive?
            arg = nil
        end
    end
    kw_vals[arg] = nil if arg
    [pos_vals, kw_vals, rest_vals]
end

#parse(tokens = ARGV) ⇒ False|OpenStruct

Note:

After parse has been called, the argument Definition used by the

Parse the specified Array<String> of tokens, or ARGV if tokens is nil. If the parse is successful, an OpenStruct object is returned with values for all defined arguments as members of the OpenStruct. If parsing is not succssful, it may be due to parse errors or because a help flag was encountered. The show_usage or show_help flags will be set (the former in the case of parse errors, and the latter if help was requested), as well as the errors property if there were parse errors.

parser may have been replaced if a command argument value was specified. This new definition can be used to show context-specific help or usage details.

an OpenStruct with accessors for every defined argument if the parse was successful. Arguments whose values are not specified will contain the agument default value, or nil if no default is specified.

Parameters:

  • tokens (Array<String>) (defaults to: ARGV) —

    The tokens to be parsed using the argument definition set for this parser. If not specified, defaults to ARGV.

Returns:

  • (False|OpenStruct) —

    false if unable to parse successfully, or



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# File 'lib/arg-parser/parser.rb', line 64

def parse(tokens = ARGV)
    @show_usage = nil
    @show_help = nil
    @errors = []
    begin
        pos_vals, kw_vals, rest_vals = classify_tokens(tokens)
        args = process_args(pos_vals, kw_vals, rest_vals) unless @show_help
    rescue NoSuchArgumentError => ex
        self.errors << ex.message
        @show_usage = true
    end
    (@show_usage || @show_help) ? false : args
end

#process_args(pos_vals, kw_vals, rest_vals) ⇒ Object

Process arguments using the supplied pos_vals Array of positional argument values, and the kw_vals Hash of keyword/value.



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# File 'lib/arg-parser/parser.rb', line 184

def process_args(pos_vals, kw_vals, rest_vals)
    result = {}

    # Process positional arguments
    pos_args = @definition.positional_args
    pos_args.each_with_index do |arg, i|
        break if i >= pos_vals.length
        result[arg.key] = process_arg_val(arg, pos_vals[i], result)
    end
    if pos_vals.size > pos_args.size
        if @definition.rest_args?
            rest_vals = pos_vals[pos_args.size..-1] + rest_vals
        else
            self.errors << "#{pos_vals.size} positional #{pos_vals.size == 1 ? 'argument' : 'arguments'} #{
                pos_vals.size == 1 ? 'was' : 'were'} supplied, but only #{pos_args.size} #{
                pos_args.size == 1 ? 'is' : 'are'} defined"
        end
    end

    # Process key-word based arguments
    kw_vals.each do |arg, val|
        result[arg.key] = process_arg_val(arg, val, result)
    end

    # Process rest values
    if rest_vals.size > 0
        if rest_arg = @definition.rest_args
            result[rest_arg.key] = process_arg_val(rest_arg, rest_vals, result)
        else
            self.errors << "#{rest_vals.size} rest #{rest_vals.size == 1 ? 'value' : 'values'} #{
                rest_vals.size == 1 ? 'was' : 'were'} supplied (#{rest_vals.join(', ')
                }), but no rest argument is defined"
        end
    end

    # Default unspecified arguments
    @definition.args.select{ |arg| !result.has_key?(arg.key) }.each do |arg|
        result[arg.key] = process_arg_val(arg, arg.default, result, true)
    end

    # Validate if any set requirements have been satisfied
    self.errors.concat(@definition.validate_requirements(result))
    if self.errors.size > 0
        @show_usage = true
    elsif result.empty?
        EmptyArgs.new
    else
        props = result.keys
        @definition.args.each{ |arg| props << arg.key unless result.has_key?(arg.key) }
        args = Struct.new(*props)
        args.new(*result.values)
    end
end

#show_help? ⇒ Boolean

Returns Flag set during parsing if the user has requested the help display to be shown (via –help or /?).

Returns:

  • (Boolean) —

    Flag set during parsing if the user has requested the help display to be shown (via –help or /?).



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# File 'lib/arg-parser/parser.rb', line 24

def show_help?
    @show_help
end

#show_usage? ⇒ Boolean

Returns Flag set during parsing if the usage display should be shown. Set if there are any parse errors encountered.

Returns:

  • (Boolean) —

    Flag set during parsing if the usage display should be shown. Set if there are any parse errors encountered.



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# File 'lib/arg-parser/parser.rb', line 19

def show_usage?
    @show_usage
end