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parsingcompiler-construction

Difference between compilers and parsers?

By concept/function/implementation, what are the differences between compilers and parsers?

Solution

  • A compiler is often made up of several components, one of which is a parser. A common set of components in a compiler is:

    • Lexer - break the program up into words.
    • Parser - check that the syntax of the sentences are correct.
    • Semantic Analysis - check that the sentences make sense.
    • Optimizer - edit the sentences for brevity.
    • Code generator - output something with equivalent semantic meaning using another vocabulary.
    To add a little bit:

    As mentioned elsewhere, small C is a recursive decent compiler that generated code as it parsed. Basically syntactical analysis, semantic analysis, and code generation in one pass. As I recall, it also lexed in the parser.

    A long time ago, I wrote a C compiler (actually several: the Introl-C family for microcontrollers) that used recursive descent and did syntax and semantic checking during the parse and produced a tree representation of the program from which code was generated.

    Today, I'm working on a compiler that does source -> tokens -> AST -> IR -> code, pretty much as I described above.