Download PCLEX Manual - Abraxas Software

Page 3
6. Write the Auxiliary C Code .........................................................................65
7. Build the Program ........................................................................................66
IX. Principles Behind PCLEX......................................................................................68
1. Introduction to Formal Languages ...............................................................68
2. Regular Expressions.....................................................................................69
3. Regular Languages .......................................................................................70
4. Non deterministic Finite State Machines (NDFSM)....................................70
5. Deterministic Finite State Machines (DFSM)..............................................71
6. PCLEX -- From Regular Expressions to DFSM ..........................................71
X. Writing PCLEX Syntax Descriptions......................................................................74
1. Regular Expressions.....................................................................................75
1.1 Operators ........................................................................................75
1.2 Character Classes ...........................................................................76
1.3 Repetition .......................................................................................76
1.4 Arbitrary Character.........................................................................76
1.5 Alternation and Grouping...............................................................77
1.6 Optional Expressions .....................................................................77
1.7 Context Sensitivity .........................................................................77
2. Actions .........................................................................................................78
3. Ambiguous Rules .........................................................................................78
4. Definitions....................................................................................................79
5. Context Sensitivity .......................................................................................80
5.1 Actions and User Subroutines ........................................................80
5.2 Start Conditions..............................................................................81
5.3 Exclusive Start Conditions.............................................................82
5.4 Special Position Anchors ...............................................................83
Appendix A. Installation ..............................................................................................84
PCLEX Users' Manual - Printed December 11, 2000