Semantic Actions

• A parser usually does more than just recognize syntax.
• It could:
  • Evaluate code (simple interpreter)
  • Emit code (single pass compiler)
  • Build an internal data structure (multi pass compiler, interpreter)
• Generally, a parser performs semantic actions
• In a machine-generated bottom-up parser, they are added to the grammar submitted to the parser generator.
• In a recursive descent parser, semantic actions are embedded in the recognizer routines.