-
Book Overview & Buying
-
Table Of Contents
PHP 7 Programming Blueprints
By :
Interpreters and compilers read programs that are formulated in a programming language. They either execute them directly (interpreters) or first convert them into a machine language or another programming language (compilers). Both interpreters and compilers usually have (among others) two components called lexer and parser.

This is a basic architecture of a compiler or interpreter
An interpreter may omit the code generation and run the parsed program directly without a dedicated compilation step.
The lexer (also called scanner or tokenizer) dissects an input program into its smallest possible parts, the so-called tokens. Each token consists of a token class (for example, numerical value or variable identifier) and the actual token contents. For example, a lexer for a calculator given the input string 2 + (3 * a) might generate the following list of tokens (each having a token class and value):
Number ("2")
Addition operator ("+")
Opening bracket ("(")
Number...