projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| d8649de5 C |
1 | .TH LEX 1 "7 February 1983" |
| 2 | .SH NAME | |
| 3 | lex \- generator of lexical analysis programs | |
| 4 | .SH SYNOPSIS | |
| 5 | .B lex | |
| 6 | [ | |
| 7 | .B \-tvfn | |
| 8 | ] [ file ] ... | |
| 9 | .SH DESCRIPTION | |
| 10 | .I Lex | |
| 11 | generates programs to be used in simple lexical analyis of text. | |
| 12 | The input | |
| 13 | .I files | |
| 14 | (standard input default) contain regular expressions | |
| 15 | to be searched for, and actions written in C to be executed when | |
| 16 | expressions are found. | |
| 17 | .PP | |
| 18 | A C source program, 'lex.yy.c' is generated, to be compiled thus: | |
| 19 | .IP | |
| 20 | cc lex.yy.c \-ll | |
| 21 | .LP | |
| 22 | This program, when run, copies unrecognized portions of | |
| 23 | the input to the output, and executes the associated | |
| 24 | C action for each regular expression that is recognized. | |
| 25 | .PP | |
| 26 | The options have the following meanings. | |
| 27 | .TP | |
| 28 | .B \-t | |
| 29 | Place the result on the standard output instead of in file "lex.yy.c". | |
| 30 | .TP | |
| 31 | .B \-v | |
| 32 | Print a one-line summary of statistics of the generated analyzer. | |
| 33 | .TP | |
| 34 | .B \-n | |
| 35 | Opposite of | |
| 36 | .BR \-v ; | |
| 37 | .B \-n | |
| 38 | is default. | |
| 39 | .TP | |
| 40 | .B \-f | |
| 41 | "Faster" compilation: don't bother to pack | |
| 42 | the resulting tables; limited to small programs. | |
| 43 | .SH EXAMPLE | |
| 44 | .IP | |
| 45 | lex lexcommands | |
| 46 | .PP | |
| 47 | would draw | |
| 48 | .I lex | |
| 49 | instructions from the file | |
| 50 | .I lexcommands, | |
| 51 | and place the output in | |
| 52 | .I lex.yy.c | |
| 53 | .IP "" | |
| 54 | .nf | |
| 55 | .ta \w'[A\-Z] 'u | |
| 56 | %% | |
| 57 | [A\-Z] putchar(yytext[0]+\'a\'\-\'A\'); | |
| 58 | [ ]+$ | |
| 59 | [ ]+ putchar(\' \'); | |
| 60 | .fi | |
| 61 | .PP | |
| 62 | is an example of a | |
| 63 | .I lex | |
| 64 | program that would be put into a | |
| 65 | .I lex | |
| 66 | command file. This program converts upper case to lower, | |
| 67 | removes blanks at the end of lines, | |
| 68 | and replaces multiple blanks by single blanks. | |
| 69 | .SH "SEE ALSO" | |
| 70 | yacc(1), sed(1) | |
| 71 | .br | |
| 72 | M. E. Lesk and E. Schmidt, | |
| 73 | .I LEX \- Lexical Analyzer Generator |