Added interfaces

Author: didix16

composer.json

@@ -1,7 +1,7 @@
 {
   "name": "didix16/php-grammar",
   "type": "library",
-  "description": "A simple library to make Lexer and Parsers to build a language",
+  "description": "A simple library for make Lexer and Parsers to build a language",
   "keywords": ["lexer", "parser", "token", "grammar", "tokenizer", "simple", "build"],
   "homepage": "https://github.com/didix16/php-grammar",
   "license": "MIT",

src/Lexer.php

@@ -7,7 +7,7 @@
  * Class Lexer
  * @package didix16\Grammar
  */
-abstract class Lexer {
+abstract class Lexer  implements LexerInterface {
 
     const NULL_TOKEN_TYPE = Token::NULL_TOKEN_VALUE;
     const NULL_TOKEN_VALUE = Token::NULL_TOKEN_TYPE;

src/LexerInterface.php

@@ -0,0 +1,55 @@
+<?php
+
+namespace didix16\Grammar;
+
+/**
+ * Interface LexerInterface
+ * @package didix16\Grammar
+ */
+interface LexerInterface {
+
+    public function __construct(string $input);
+
+    /**
+     * From input string, consume a character by default.
+     * This method may be override to consume a word or some regexp
+     * @return $this
+     */
+    public function consume(): self;
+
+    /**
+     * Check if current character is an ASCII letter
+     * @return bool
+     */
+    public function isLetter();
+
+    /**
+     * Consume contiguous white spaces
+     */
+    public function WS();
+
+    /**
+     * Returns the last character readed by this lexer
+     * @return string
+     */
+    public function lastCharacter(): string;
+
+    /**
+     * Return the last token founded
+     * @return Token
+     */
+    public function lastToken(): Token;
+
+    /**
+     * Returns the next token identified by this lexer
+     * @return Token
+     */
+    public function nextToken(): Token;
+
+    /**
+     * Given a token type returns its token name
+     * @param $tokenType
+     * @return string
+     */
+    public function getTokenName($tokenType): string;
+}

src/Parser.php

@@ -8,17 +8,17 @@
  * Class Parser
  * @package didix16\Grammar
  */
-abstract class Parser {
+abstract class Parser implements ParserInterface {
 
     /**
      * The lexer from we get the tokens
-     * @var Lexer
+     * @var LexerInterface
      */
     protected $input;
 
     /**
      * Current lookahead Token
-     * @var Token
+     * @var TokenInterface
      */
     protected $lookahead;
 
@@ -28,7 +28,7 @@ abstract class Parser {
      */
     protected $tokenList = [];
 
-    public function __construct(Lexer $input)
+    public function __construct(LexerInterface $input)
     {
         $this->input = $input;
         $this->lookahead = $this->input->nextToken();
@@ -73,7 +73,7 @@ public function getTokens(){
     /**
      * The main entry point of the grammar expression
      * Returns the list of tokens founded
-     * @return array
+     * @return TokenInterface[]
      */
     public abstract function parse() : array ;
 

src/ParserInterface.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace didix16\Grammar;
+
+/**
+ * Interface ParserInterface
+ * @package didix16\Grammar
+ */
+interface ParserInterface {
+
+    public function __construct(LexerInterface $input);
+
+    /**
+     * If token type passed matches the expected token type then consume next token
+     * else throws an exception
+     * @param $tokenType
+     * @throws Exception
+     */
+    public function match($tokenType);
+
+    /**
+     * Consume current token and store it to token list
+     */
+    public function consume();
+
+    /**
+     * Get all the evaluated tokens
+     * @return array
+     */
+    public function getTokens();
+
+    /**
+     * The main entry point of the grammar expression
+     * Returns the list of tokens founded
+     * @return array
+     */
+    public function parse() : array ;
+}

src/Token.php

@@ -8,7 +8,7 @@
  * Class Token
  * @package didix16\Grammar
  */
-class Token
+class Token implements TokenInterface
 {
     const NULL_TOKEN_TYPE = 0;
     const NULL_TOKEN_VALUE = NULL;

src/TokenInterface.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace didix16\Grammar;
+
+/**
+ * Interface TokenInterface
+ * @package didix16\Grammar
+ */
+interface TokenInterface {
+
+     /**
+     * Token constructor.
+     * @param $type
+     * @param $value
+     */
+    public function __construct($type, $value);
+
+    /**
+     * Returns a representation of this token
+     */
+    public function __toString(): string;
+
+    /**
+     * Returns the type of the token
+     */
+    public function getType();
+
+    /**
+     * Returns the value this token is holding
+     */
+    public function getValue();
+
+}