Class: ArgParser::Parser

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

Overview

Parser for parsing a command-line

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 32

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 59

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 8

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 11

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



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# File 'lib/arg-parser/parser.rb', line 73

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
    tokens.each_with_index do |token, i|
        case token
        when '/?', '-?', '--help'
            @show_help = true
        when /^-([a-z0-9]+)/i
            $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
                end
            end
        when /^(?:--|\/)(no-)?(.+)/i
            kw_vals[arg] = nil if arg
            arg = @definition[$2]
            if FlagArgument === arg || (KeywordArgument === arg && $1)
                kw_vals[arg] = $1 ? false : true
                arg = nil
            end
        when '--'
            # All subsequent values are rest args
            kw_vals[arg] = nil if arg
            rest_vals = tokens[(i + 1)..-1]
            break
        else
            if arg
                kw_vals[arg] = token
            else
                pos_vals << token
                arg = @definition.positional_args[i]
            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) ⇒ Object

Parse the specified Array of tokens, or ARGV if tokens is nil. Returns false if unable to parse successfully, or an OpenStruct with accessors for every defined argument. Arguments whose values are not specified will contain the agument default value, or nil if no default is specified.



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# File 'lib/arg-parser/parser.rb', line 43

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 127

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_arg = @definition.rest_args
        result[rest_arg.key] = process_arg_val(rest_arg, rest_vals, result)
    elsif rest_vals.size > 0
        self.errors << "#{rest_vals.size} rest #{rest_vals.size == 1 ? 'value' : 'values'} #{
            rest_vals.size == 1 ? 'was' : 'were'} supplied, but no rest argument is defined"
    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?
        BasicObject.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 19

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 14

def show_usage?
    @show_usage
end