Last active
August 29, 2015 13:56
-
-
Save jsl/8985707 to your computer and use it in GitHub Desktop.
Dictionary Replacer
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| require 'minitest/autorun' | |
| require 'stringio' | |
| class DictionaryReplacer | |
| MARK = '$' | |
| ESCAPE = '\\' | |
| def initialize(to_replace, dictionary) | |
| @to_replace = StringIO.new(to_replace) | |
| @dictionary = dictionary | |
| end | |
| def translate | |
| result = '' | |
| key = '' | |
| in_match = false | |
| escaping = false | |
| while c = @to_replace.getc | |
| if c == ESCAPE | |
| escaping = true | |
| result += c | |
| elsif escaping | |
| result += c | |
| escaping = false | |
| elsif c == MARK | |
| in_match = !in_match | |
| if in_match | |
| key = '' | |
| else | |
| if translation = @dictionary[key.to_sym] | |
| result += translation | |
| else | |
| raise SyntaxError | |
| end | |
| end | |
| else | |
| if in_match | |
| key += c | |
| else | |
| result += c | |
| end | |
| end | |
| end | |
| raise SyntaxError if in_match | |
| result | |
| end | |
| end | |
| describe "dictionary replacement" do | |
| describe "converting strings" do | |
| it "converts matching strings" do | |
| DictionaryReplacer.new('foo $bar$', {bar: 'baz'}).translate. | |
| must_equal 'foo baz' | |
| end | |
| it "doesn't consider escaped MARKs as tokens" do | |
| DictionaryReplacer.new('foo\$ $bar$', {bar: 'baz'}).translate. | |
| must_equal 'foo\$ baz' | |
| end | |
| it "converts strings with two substitutions" do | |
| DictionaryReplacer.new('foo $bar$ what $fizz$', | |
| {bar: 'baz', fizz: 'faz'}).translate. | |
| must_equal 'foo baz what faz' | |
| end | |
| it "raises a SyntaxError when the token is not found in the dictionary" do | |
| -> { DictionaryReplacer.new('$foo$',{ }).translate }. | |
| must_raise SyntaxError | |
| end | |
| it "raises an error if the input string is invalid" do | |
| -> { DictionaryReplacer.new('$foo$ $', {foo: 'bar'}).translate }. | |
| must_raise(SyntaxError) | |
| end | |
| end | |
| end |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment