### 0.5.09 / 2017-12-02
* [CHANGE] Dir `examples/general/SRL/ Added support for letter range to Simple Regex Language parser.

### 0.5.08 / 2017-11-28
* [NEW] Dir `examples/general/SRL/ Added an initial version of the Simple Regex Language parser.
  Supports the SRL quantifier syntax only.
* [FIX] Method `ParseTreeBuilder::place_TOS_child` was sometimes fooled when argument `aNode` was nil.
* [FIX] Method `BaseParser::initialize` missing parameter name in doc caused a YARD warning.
* [FIX] Method `GrmItemsBuilder::build_dotted_items` missing parameter name in doc caused a YARD warning.
* [FIX] Method `NonTerminalVertex::initialize` missing parameter name in doc caused a YARD warning.


### 0.5.07 / 2017-11-11
* [NEW] File `benchmark_mini_en.rb` added in `examples/NLP` folder for parsing performance measurements.
* [CHANGE] Demo calculator in `examples/general/calc_iter2`: added support for log10 and cbrt functions. README.md slightly reworked.
* [FIX] File `README.md` sample code was broken by changes in 0.5.06 (thanks to arjunmenon for pointing this).

### 0.5.06 / 2017-11-08
* [CHANGE] Demo calculator in `examples/general/calc_iter2` does much than the basic arithmetic operators, it now  
support trigonometric functions and their inverse, square root, exponential and natural logarithm functions!.
* [CHANGE] Internal module re-organization. New module `Base`, module `Tokens` renamed to `Lexical`.
* [CHANGE] Improved YARD Documentation for 10+ classes.

### 0.5.05 / 2017-11-04
* [FIX] Method `GFGParsing#call_rule` didn't handle properly the case of nullable symbols appearing in more than one production rule.
* [New] New calculator example. In addition to the basic arithmetic operators (+, -, *, /) it accepts the unary minus
  and the exponentiation operator. As a convenience it displays both CST and AST parse representations.
* [CHANGE] Method `ParseWalkerFactory#build_walker` added one argument that controls the way the visit when reaching anew an end vertex.
* [CHANGE] Method `ParseWalkerFactory#visit_entry` when re-visit an end vertex, the jump to related start vertex is now conditional.
* [CHANGE] File `parse_walker_factory_spec.rb` Added test to validate the different ways to walk over the parse entries.
* [CHANGE] Class `GrmFlowGraph`: Added more documentation.
* [CHANGE] Class `Vertex`: Documentation refined.

### 0.5.04 / 2017-10-26
* [Fix] Method GrmFlowGraph#traverse_df code terminated prematurely with nested call edges.
* [CHANGE] Method Grammar#name_production: suffix in default production name is changed (e.g. 'expression[3]' changed to expression_3)

### 0.5.03 / 2017-10-09
* [CHANGE] Refactoring code style to please Rubocop 0.50.0
* [CHANGE] File `.rubocop.yml`: Disabling heredoc cop because it produces false negatives
* [FIX] File `examples/general/calc_iter1/calc_ast_builder.rb`. Method CalcASTBuilder#new_leaf_node used old signature. Fixed

### 0.5.02 / 2017-10-08
* [NEW] Addedsupport for ASTs (Abstract Syntax Tree)
* [CHANGE] File `examples/data_formats/JSON/JSON_demo.rb` Added New command-line switches for details use --help option
* [CHANGE] File `examples/general/calc_iter1/calc_demo.rb` Calculator now computes the value of a parsed expression

### 0.5.01 / 2017-08-20
* [CHANGE] File `appveyor.yml`: Added Ruby 2.4 build environment in Appveyor CI


### 0.5.00 / 2017-08-20
* [CHANGE] Concrete Syntax tree generation re-designed in prevision of customized tree generation.
* [NEW] Class `Parser::CSTBuilder` Builder class that creates Concrete Syntax (parse) Tree.


### 0.4.08 / 2017-08-06
* [FIX] File `/spec/spec_helper.rb` replaced deprecated syntax for `SimpleCov::Formatter::MultiFormatter` construction
* [NEW] File `examples/data_formats/JSON/json_minifier.rb` Added a working JSON minifier to the demo app.
* [NEW] Class `Syntax::Production` Each production can have a name.
* [CHANGE] File `.travis.yml`: removal of Rubinius (rbx) in the list of Ruby versions.
* [CHANGE] DRYing the classes `ParseTreeFactory` and `ParseForestFactory` by inheriting from  `ParseRepCreator`
* [CHANGE] Minor documentation updates.

### 0.4.07 / 2017-05-25
* [FIX] To avoid Fixnum deprecation error in Ruby 2.4 and higher, all explicit references to Fixnum has been removed.
* [FIX] File `.rubocop.yml`: folder `examples` was excluded from Rubocop control. Now it is in code analysis scope.
* [NEW] File `spec/.rubocop.yml` to tune the code analysis for Rspec files
* [NEW] File `examples\.rubocop.yml` to tune the code analysis for example files
* [CHANGE] Code re-styling to please Rubocop 0.49.0: less than 10 offences remain (from above 200 count!)
* [CHANGE] Added support for Ruby 2.4.x. Files `.travis.yml` and `README.md` updated.


### 0.4.06 / 2017-05-25
* [FIX] File `formatter/asciitree.rb` fixed inconsistency in comments that caused Yard warnings.
* [FIX] File `formatter/bracket_notation.rb` fixed inconsistency in comments that caused Yard warnings.
* [FIX] File `parser/parse_entry_set.rb` fixed inconsistency in comments that caused Yard warnings.
* [NEW] Method `Grammar#diagnose` performs a number of checks on the grammar. It detects whether:  
  there are undefined non-terminals (i.e. non-terminals without a rule that define them)
  there are non-productive non-terminals (i.e. non-terminals that don't derive a sting of terminals)
  there are nullable productions and non-terminals.
* [NEW] Method `GrmFlowGraph#traverse_df` performs depth-first traversal of the GFG.
* [NEW] Method `GrmFlowGraph#diagnose` determines which terminals are reachable from the start symbol.
* [NEW] Method `GrmSymbol#generative?` inidcates whether the grammar symbol can produce a sequence of terminals.
* [CHANGE] Class `GrammarBuilder` Improved the API documentation.

### 0.4.05 / 2017-05-06
* [CHANGE] File `README.md` Added documentation on how to build parse trees and manipulate them.
* [CHANGE] File `examples/NLP/mini_en_demo.rb` now emits different parse tree representations.
* [NEW] Directory `www`. Contains a diagram output produced from Rley and fed to online RSyntaxTree tool.

### 0.4.04 / 2017-05-01
* [NEW] `Asciitree` formatter class. Allows parse tree output in simple printable text.
* [CHANGE] Major enhancements in directory `examples\data_formats\JSON`. The demo command-line tool parses JSON and outputs the parse tree in one of the supported formats.

### 0.4.03 / 2017-04-17
* [FIX] File `rley.rb` reference to obsolete `EarleyParser` class removed.
* [NEW] `BracketNotation` formatter class. Allows parse tree output in Labelled Bracket Notation.
* [CHANGE] Code refactoring in directory `examples\data_formats\JSON`. The demo command-line tool parses JSON and converts it into LBN (Labelled Bracket Notation). There are two diagrams (in SVG format) generated from the LBN output.

### 0.4.02 / 2017-04-09
* [NEW] Module re-organization for clearer dependencies: Classes `Token` and `TokenRange` are moved to a separate module `Tokens`.
* [CHANGE] Code, specs, examples and `README.md` adapted to reflect the module re-organization.

### 0.4.01 / 2016-12-21
* [NEW] File `appveyor.yml`. Add AppVeyor CI to Github commits. AppVeyor complements Travis by running builds under Windows OS.
  This permits to test the portability across operating systems.
* [CHANGE] File `README.md` Added AppVeyor badge.
* [CHANGE] File `rley.gemspec` drop support for Ruby 1.9.3. Lowest supported Ruby version is now 2.0.0.
* [CHANGE] File `.travis.yml` updated list of Ruby versions to use by Travis CI

### 0.4.00 / 2016-12-17
* [CHANGE] Error reporting is vastly changed. Syntax errors don't raise exceptions.
  parse error can be retrieved via an `ErrorReason` object. Such an object is returned by the
  method `GFGParsing#failure_reason` method.
* [CHANGE] File `README.md` updated to reflect the new error reporting.
* [CHANGE] Examples updated to reflect the new error reporting.  

### 0.3.12 / 2016-12-08
* [NEW] Directory `examples\general\calc`. A simple arithmetic expression demo parser.

### 0.3.11 / 2016-12-04
* [NEW] Directory `examples\data_formats\JSON`. A JSON demo parser.

### 0.3.10 / 2016-12-04
* [NEW] Method `ParseForest#ambiguous?`. Indicates whether the parse is ambiguous.
* [CHANGE] File `README.md` updated with new grammar builder syntax & typo fixes.
* [CHANGE] Method `GrammarBuilder#initialize`: Accepts a block argument that allows lighter construction.

### 0.3.09 / 2016-11-27
* [CHANGE] File `README.md` fully rewritten and added an example.
* [CHANGE] Directory `examples` completely reorganized.

### 0.3.09 / 2016-11-27
* [CHANGE] File `README.md` fully rewritten and added an example.
* [CHANGE] Directory `examples` completely reorganized.

### 0.3.08 / 2016-11-17
* [FIX] Method `ParseWalkerFactory#select_antecedent` did not support alternative nodes creation when visiting an item entry for highly ambiguous parse.
* [FIX] Method `ParseWalkerFactory#select_antecedent` did not manage properly call/return stack for alternative nodes created when visiting an item entry for highly ambiguous parse.


### 0.3.07 / 2016-11-08
* [FIX] The sharing a of forest node could be repeated in a production in a revisit event.
* [CHANGE] Method `ParseWalkerFactory#process_end_entry`. Added a guard condition to avoid repeated node sharing
* [NEW] RSpec file `ambiguous_parse_spec.rb` added in order to test the fix.

### 0.3.06 / 2016-11-06
* [FIX] There were missing links to shared parse forest nodes for ambiguous parses.
* [NEW] RSpec file `ambiguous_parse_spec.rb` added in order to test the parse forest building for an ambiguous parse.
* [CHANGE] Attribute `ParseWalkerContext#nterm2start`: previous implementation assumed -wrongly- that for each non terminal there was only one start entry.
  Now this attribute uses nested hashes as data structure in order to disambiguate the mapping.
* [CHANGE] Method `ParseWalkerFactory#visit_entry` updated to reflect change in the `ParseWalkerContext#nterm2start` attribute.
* [CHANGE] Method `ParseWalkerFactory#visit_entry` now emits an event if an item entry is re-visited (previously, no such event were generated)

### 0.3.05 / 2016-11-01
* [CHANGE] Code re-styling to please Rubocop 0.45.0: only 2 offences remain (from a few hundreds!)

### 0.3.04 / 2016-11-01
* [FIX] File `state_set_spec.rb` : Failing mock tests. Reverted `expect` to `allow` expectations.

### 0.3.03 / 2016-11-01
* [FIX] File `parse_forest_factory_spec.rb`: Commented out reference to local files.
* [FIX] Files `*_spec.rb` : Replaced most `allow` expectations by `expect`
* [CHANGE] Updated development dependency upon RSpec version 3.5

### 0.3.02 / 2016-11-01
* [FIX] Method `ParseWalkerFactory#visit_entry` didn't generate events for entries with start vertex. This caused issue in parse forest generation.
* [NEW] File `parse_forest_builder_spec.rb`: added more parse forest building tests.
* [CHANGE] Method `ParseWalkerFactory#antecedent_of`. Code refactoring.
* [CHANGE] Method `ParseForestBuilder#receive_event`. Code refactoring.

### 0.3.01 / 2016-10-23
* [CHANGE] Method `ParseWalkerFactory#build_walker`. Signature change in order prevent direct dependency on `GFGParsing` class.
* [CHANGE] Class `ParseForestBuilder`. Removal of `parsing` attribute, no direct dependency on `GFGParsing` class.
* [CHANGE] Internal changed to `ParseForestFactory` class.

### 0.3.00 / 2016-10-23
* [CHANGE] Many new classes. The gem bundles a second parser that copes with ambiguous grammars.


### 0.2.15 / 2016-02-14
* [CHANGE] A lot of internal changes. This is the last version before a Grammar Flow Graph-based parsing implementation.

### 0.2.14 / 2015-11-25
* [FIX] Method `StateSet#ambiguities` overlooked some ambiguities in parse sets.

### 0.2.13 / 2015-11-25
* [NEW] method `Parsing#ambiguous?` returns true if more than one successful parse tree can be retried from parse results.
* [CHANGED] method `Parsing#success?`. New implementation that relies on start symbol derivation.
* [NEW] New method `Chart#start_symbol` added. Returns the start symbol of the grammar.
* [NEW] New method `StateSet#ambiguities` added. Returns the parse sets that are ambiguous (= distinct derivation for same input tokens).
* [FIX] In special cases the parsing didn't work correctly when there more than one
    production rule for the start symbol of a grammar.

### 0.2.12 / 2015-11-20
* [FIX] In special cases the parsing didn't work correctly when there more than one
    production rule for the start symbol of a grammar.

### 0.2.11 / 2015-09-05
* [CHANGE] Code re-formatted to please Rubocop 0.34.0
* [CHANGE] File `.travis.yml`: added new Rubies: MRI 2.2.0 and JRuby 9.0.
* [CHANGE] File `rley.gemspec`: Upgraded gem versions in development dependencies
* [CHANGE] File `Gemfile`: Upgraded gem versions in development dependencies

### 0.2.10 / 2015-06-16
* [CHANGE] Code re-formatted to please Rubocop 0.32.0
* [FIX] File `.rubocop.yml`: disable some cop settings that were too loud.

### 0.2.08 / 2015-04-28
* [NEW] Added folder with JSON demo parser under `examples\parsers\demo-JSON`.

### 0.2.07 / 2015-04-22
* [NEW] Rake file added in `examples` folder. It allows to run all the examples at once.

### 0.2.06 / 2015-03-21
* [FIX] Method `EarleyParser#handle_error` portability issue between Ruby versions.


### 0.2.05 / 2015-03-19
* [NEW] Class `EarleyParser` implements a crude error detection mechanism. A syntax error causes an exception to be raised.
* [CHANGE] Examplar file `parsing_err_expr.rb`: demo error message.

### 0.2.04 / 2015-03-04
* [NEW] Class `ParseTracer` that helps to trace the parse steps (similar the trace format in NLTK).
* [CHANGE] Method `EarleyParser#parse` takes a trace level argument.


### 0.2.03 / 2015-02-06
* [FIX] File `.rubocop.yml`: removal of setting for obsolete EmptyLinesAroundBody cop.
* [CHANGE] Source code re-formatted to please Rubocop 0.29.
* [CHANGE] File `README.md` added licensing badge (MIT license)

### 0.2.02 / 2015-02-02
* [NEW] Examplar file `parsing_L1.rb`: demo using a (highly simplified) English grammar.
* [NEW] Examplar file `parsing_amb.rb`: demo using an ambiguous grammar.
* [FIX] Method `Parsing#parse_tree` now produces correct parse trees for all the examples.

### 0.2.01 / 2015-01-03
* [CHANGE] File `.rubocop.yml`: AbcMetric setting relaxed.
* [CHANGE] Fixed most style offenses reported by Rubocop.

### 0.2.00 / 2015-01-03  
Version number bump: major re-design of the parse tree generation.
* [NEW] Class `ParseTreeBuilder`: builder for creating parse tree.
* [NEW] Class `ParseStateTracker`: helper class used in parse tree generation.
* [NEW] Examplar file `parsing_L0.rb`: demo using a (highly simplified) English grammar.
* [CHANGE]  Class `ParseTree`: construction methods removed.
* [CHANGE]  Method `Parsing#parse_tree` completely rewritten.
* [FIX] Method `Parsing#parse_tree` now handles situations where there are multiple complete parse states for a non-terminal.

### 0.1.12 / 2014-12-22
* [FIX] Fixed `Parsing#parse_tree`: code couldn't cope with parse state set containing more
  than one parse state that expected the same symbol.
* [NEW] Added one more parser example (for very basic arithmetic expression)

### 0.1.11 / 2014-12-16
* [FIX] Fixed all but one YARD (documentation) warnings. Most of them were due to mismatch
in method argument names between source code and documentation.  
* [CHANGE] File `README.md` added Gemnasium badge (for the gem dependency checks)

### 0.1.10 / 2014-12-14
* [CHANGE] Added more examples in `examples` folder (e.g. parsing then parse tree ).
* [CHANGE] File `rley.rb`: added more requires of the library to ease integration.

### 0.1.09 / 2014-12-14
* [CHANGE] Source code refactored to please Rubocop (0.28.0)
* [CHANGE] File `.rubucop.yml`  Disabled VariableNam style cop.

### 0.1.08 / 2014-12-13
* [CHANGE] File `README.md` added coveralls badge (for the test coverage)

### 0.1.07 / 2014-12-13
* [NEW] Added development dependency on 'coveralls' gem (for test coverage measurement)

### 0.1.06 / 2014-12-13
* [NEW] New parse tree formatting class `JSON` for parse tree rendition in JSON.
* [FIX] Method `Parsing#parse_tree` now add link to Token object for last TerminalNode in tree.

### 0.1.05 / 2014-12-10
* [NEW] New parse tree formatting classes `BaseFormatter` and `Debug`
* [CHANGE] Method `Parsing#parse_tree` now add links to Token objects in TerminalNodes.

### 0.1.04 / 2014-12-08
* [CHANGE] File `parse_tree_visitor_spec.rb`. Added step-by-step test of a parse tree visit.


### 0.1.03 / 2014-12-08
* [NEW] `ParseTreeVisitor` class. A class that walks through a parse tree.
* [NEW] Method `accept` added to `ParseTree`, `TerminalNode`, `NonTerminalNode` classes.

### 0.1.02 / 2014-12-06
* [CHANGE] Upgraded code & spec files to reach 100% code coverage again.


### 0.1.01 / 2014-12-06
* [CHANGE] Restaured test coverage to above 99%

### 0.1.00 / 2014-12-05
* [CHANGE] Bumped version number: it is the first version able to generate a parse tree.
* [NEW] `Grammar#name2symbol` attribute and accessor. Retrieve a grammar symbol from its name.
* [NEW] Methods `DottedItem#prev_symbol`, `DottedItem#prev_position` to find symbol on left of dot.
* [NEW] Method `ParseState#precedes?`, predicate to check whether self is a predecessor of given parse state.
* [NEW] Method `Parsing#parse_tree` returns a ParseTree object that represents the result of a parse.


### 0.0.18 / 2014-11-23
* [CHANGE] `EarleyParser#parse`: Optimization prevent repeated prediction of same non-terminal for same state set.
* [CHANGE] File `earley_parser_spec.rb`: Added new test for nullable grammar.
* [CHANGE] Style refactoring in classes `EarleyParser`, `StateSet`, `Grammar`, `NonTerminal`

### 0.0.17 / 2014-11-23
* [CHANGE] File `earley_parser_spec.rb`: Added step-by-step test of ambiguous grammar parsing.

### 0.0.16 / 2014-11-23
* [NEW]  Method `DottedItem#to_s` Returns a text representation of an instance.
* [NEW]  Method `ParseState#to_s`
* [NEW]  Method `GrmSymbol#to_s`
* [NEW]  Method `VerbatimSymbol#to_s`
* [CHANGE] File `earley_parser_spec.rb`: Parse tests refactored.


### 0.0.15 / 2014-11-20
* [FIX]  `EarleyParser` class source code was out-of-sync.

### 0.0.14 / 2014-11-20
* [NEW]  `EarleyParser` now supports grammar with empty productions (i.e. nullable nonterminals).
* [CHANGE]  (private) method `EarleyParser#prediction` updated with Ayock-Horspool improvement.
* [CHANGE]  Moved class `DottedItem` under the `Parser` module.

### 0.0.13 / 2014-11-19
* [NEW]  (private) method `Grammar#compute_nullable` added.
* [CHANGE] `Grammar#initialize` constructor calls the method `Grammar#compute_nullable`


### 0.0.12 / 2014-11-17
* [CHANGE]  Classes `Terminal` and `NonTerminal` added new method nullable?
* [CHANGE] File `earley_parser_spec.rb`: Added spec with ambiguous grammar.


### 0.0.11 / 2014-11-16
* [CHANGE]  Usage of `GrammarBuilder`simplified: the call to method `GrammarBuilder#add_non_terminal` isn't necessary. Method is removed
* [CHANGE] Updated the `examples` folder accordingly.

### 0.0.10 / 2014-11-15
* [NEW]  New folder `examples` added with two examples of grammar creation

### 0.0.09 / 2014-11-15
* [NEW]  New class `GrammarBuilder` added and tested, its purpose is
to simplify the construction of grammars.

### 0.0.08 / 2014-11-14
* [CHANGE]  `EarleyParser#parse` method: Initial API documentation.
* [INFO] This version was committed to force Travis CI to execute a complete build
failed because Travis couldn't connect to GitHub)

### 0.0.07 / 2014-11-14
* [CHANGE]  spec file of `EarleyParser` class: Test added. Parser works with simple expression grammar.

### 0.0.06 / 2014-11-13
* [CHANGE] File `README.md`: Added roadmap section.
* [FIX] `EarleyParser#parse`: prevent call to `scanning` method after last token encountered.

### 0.0.05 / 2014-11-13
* [CHANGE] Code re-styling to please Rubocop 0.27.0 (less than 10 offenses).

### 0.0.04 / 2014-11-12
* [CHANGE] Class `DottedItem` moved to `Rley` module.

### 0.0.03 / 2014-11-12
* [CHANGE] File `README.md`: Added gem version badge.


### 0.0.02 / 2014-11-12
* [CHANGE] File `README.md`: Added Travis CI badge.


### 0.0.01 / 2014-11-12
* [CHANGE] Rley is "gemmified"!


### 0.0.00 / 2014-11-07
* [FEATURE] Initial public working version