(flex.info)FAQ
FAQ
***
From time to time, the 'flex' maintainer receives certain questions.
Rather than repeat answers to well-understood problems, we publish them
here.
When was flex born?- How do I expand backslash-escape sequences in C-style quoted strings?
- Why do flex scanners call fileno if it is not ANSI compatible?
- Does flex support recursive pattern definitions?
- How do I skip huge chunks of input (tens of megabytes) while using flex?
- Flex is not matching my patterns in the same order that I defined them.
- My actions are executing out of order or sometimes not at all.
- How can I have multiple input sources feed into the same scanner at the same time?
- Can I build nested parsers that work with the same input file?
- How can I match text only at the end of a file?
- How can I make REJECT cascade across start condition boundaries?
- Why cant I use fast or full tables with interactive mode?
- How much faster is -F or -f than -C?
- If I have a simple grammar cant I just parse it with flex?
- Why doesn't yyrestart() set the start state back to INITIAL?
- How can I match C-style comments?
- The period isn't working the way I expected.
- Can I get the flex manual in another format?
- Does there exist a "faster" NDFA->DFA algorithm?
- How does flex compile the DFA so quickly?
- How can I use more than 8192 rules?
- How do I abandon a file in the middle of a scan and switch to a new file?
- How do I execute code only during initialization (only before the first scan)?
- How do I execute code at termination?
- Where else can I find help?
- Can I include comments in the "rules" section of the file?
- I get an error about undefined yywrap().
- How can I change the matching pattern at run time?
- How can I expand macros in the input?
- How can I build a two-pass scanner?
- How do I match any string not matched in the preceding rules?
- I am trying to port code from AT&T lex that uses yysptr and yysbuf.
- Is there a way to make flex treat NULL like a regular character?
- Whenever flex can not match the input it says "flex scanner jammed".
- Why doesn't flex have non-greedy operators like perl does?
- Memory leak - 16386 bytes allocated by malloc.
- How do I track the byte offset for lseek()?
- How do I use my own I/O classes in a C++ scanner?
- How do I skip as many chars as possible?
- deleteme00
- Are certain equivalent patterns faster than others?
- Is backing up a big deal?
- Can I fake multi-byte character support?
- deleteme01
- Can you discuss some flex internals?
- unput() messes up yy_at_bol
- The | operator is not doing what I want
- Why can't flex understand this variable trailing context pattern?
- The ^ operator isn't working
- Trailing context is getting confused with trailing optional patterns
- Is flex GNU or not?
- ERASEME53
- I need to scan if-then-else blocks and while loops
- ERASEME55
- ERASEME56
- ERASEME57
- Is there a repository for flex scanners?
- How can I conditionally compile or preprocess my flex input file?
- Where can I find grammars for lex and yacc?
- I get an end-of-buffer message for each character scanned.
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- What is the difference between YYLEX_PARAM and YY_DECL?
- Why do I get "conflicting types for yylex" error?
- How do I access the values set in a Flex action from within a Bison action?
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