Lesson 5.3

• Error Handling

  The tasks are to detect each error, report it to the user, make a recovery strategy, and implement it to handle the error. The processing time of the program should not be slow
• Error Handler

  • Error Detection, Error Report, Error Recovery
• Types of Error

  • Logic errors
  • Run-time errors
  • Compile-time errors
• Logic errors occur when programs operate incorrectly but do not terminate abnormally. Unexpected or undesired outputs may result from a logic error
• A run-time error occurs during the execution of a program due to adverse system parameters or invalid input data
• Compile-time errors arise before the execution of the program, such as syntax errors or missing file references
• Classification of Compile-time error

  • Lexical
  • Syntactical
  • Semantical
  • Logical
• Error Recovery

  The basic requirement for the compiler is to stop, issue a message, and cease compilation
• Common Recovery Methods

  • Panic mode recovery
  • Phase level recovery
  • Error productions
  • Global correction
• Panic mode recovery is the easiest way of error recovery, preventing infinite loops while recovering errors
• Phase level recovery involves local correction on the remaining input to continue parsing
• Error productions can be used to generate error messages during parsing and continue the process
• Global correction involves analyzing the whole program to find the closest match for erroneous input