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Diffstat (limited to 'tool/stripccomments.c')
| -rw-r--r-- | tool/stripccomments.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/tool/stripccomments.c b/tool/stripccomments.c new file mode 100644 index 0000000..53933c0 --- /dev/null +++ b/tool/stripccomments.c @@ -0,0 +1,228 @@ +/** + Strips C- and C++-style comments from stdin, sending the results to + stdout. It assumes that its input is legal C-like code, and does + only little error handling. + + It treats string literals as anything starting and ending with + matching double OR single quotes OR backticks (for use with + scripting languages which use those). It assumes that a quote + character within a string which uses the same quote type is escaped + by a backslash. It should not be used on any code which might + contain C/C++ comments inside heredocs, and similar constructs, as + it will strip those out. + + Usage: $0 [--keep-first|-k] < input > output + + The --keep-first (-k) flag tells it to retain the first comment in the + input stream (which is often a license or attribution block). It + may be given repeatedly, each one incrementing the number of + retained comments by one. + + License: Public Domain + Author: Stephan Beal (stephan@wanderinghorse.net) +*/ +#include <stdio.h> +#include <assert.h> +#include <string.h> + +#if 1 +#define MARKER(pfexp) \ + do{ printf("MARKER: %s:%d:\t",__FILE__,__LINE__); \ + printf pfexp; \ + } while(0) +#else +#define MARKER(exp) if(0) printf +#endif + +struct { + FILE * input; + FILE * output; + int rc; + int keepFirst; +} App = { + 0/*input*/, + 0/*output*/, + 0/*rc*/, + 0/*keepFirst*/ +}; + +void do_it_all(void){ + enum states { + S_NONE = 0 /* not in comment */, + S_SLASH1 = 1 /* slash - possibly comment prefix */, + S_CPP = 2 /* in C++ comment */, + S_C = 3 /* in C comment */ + }; + int ch, prev = EOF; + FILE * out = App.output; + int const slash = '/'; + int const star = '*'; + int line = 1; + int col = 0; + enum states state = S_NONE /* current state */; + int elide = 0 /* true if currently eliding output */; + int state3Col = -99 + /* huge kludge for odd corner case: */ + /*/ <--- here. state3Col marks the source column in which a C-style + comment starts, so that it can tell if star-slash inside a + C-style comment is the end of the comment or is the weird corner + case marked at the start of _this_ comment block. */; + for( ; EOF != (ch = fgetc(App.input)); prev = ch, + ++col){ + switch(state){ + case S_NONE: + if('\''==ch || '"'==ch || '`'==ch){ + /* Read string literal... + needed to properly catch comments in strings. */ + int const quote = ch, + startLine = line, startCol = col; + int ch2, escaped = 0, endOfString = 0; + fputc(ch, out); + for( ++col; !endOfString && EOF != (ch2 = fgetc(App.input)); + ++col ){ + switch(ch2){ + case '\\': escaped = !escaped; + break; + case '`': + case '\'': + case '"': + if(!escaped && quote == ch2) endOfString = 1; + escaped = 0; + break; + default: + escaped = 0; + break; + } + if('\n'==ch2){ + ++line; + col = 0; + } + fputc(ch2, out); + } + if(EOF == ch2){ + fprintf(stderr, "Unexpected EOF while reading %s literal " + "on line %d column %d.\n", + ('\''==ch) ? "char" : "string", + startLine, startCol); + App.rc = 1; + return; + } + break; + } + else if(slash == ch){ + /* MARKER(("state 0 ==> 1 @ %d:%d\n", line, col)); */ + state = S_SLASH1; + break; + } + fputc(ch, out); + break; + case S_SLASH1: /* 1 slash */ + /* MARKER(("SLASH1 @ %d:%d App.keepFirst=%d\n", + line, col, App.keepFirst)); */ + switch(ch){ + case '*': + /* Enter C comment */ + if(App.keepFirst>0){ + elide = 0; + --App.keepFirst; + }else{ + elide = 1; + } + /*MARKER(("state 1 ==> 3 @ %d:%d\n", line, col));*/ + state = S_C; + state3Col = col-1; + if(!elide){ + fputc(prev, out); + fputc(ch, out); + } + break; + case '/': + /* Enter C++ comment */ + if(App.keepFirst>0){ + elide = 0; + --App.keepFirst; + }else{ + elide = 1; + } + /*MARKER(("state 1 ==> 2 @ %d:%d\n", line, col));*/ + state = S_CPP; + if(!elide){ + fputc(prev, out); + fputc(ch, out); + } + break; + default: + /* It wasn't a comment after all. */ + state = S_NONE; + if(!elide){ + fputc(prev, out); + fputc(ch, out); + } + } + break; + case S_CPP: /* C++ comment */ + if('\n' == ch){ + /* MARKER(("state 2 ==> 0 @ %d:%d\n", line, col)); */ + state = S_NONE; + elide = 0; + } + if(!elide){ + fputc(ch, out); + } + break; + case S_C: /* C comment */ + if(!elide){ + fputc(ch, out); + } + if(slash == ch){ + if(star == prev){ + /* MARKER(("state 3 ==> 0 @ %d:%d\n", line, col)); */ + /* Corner case which breaks this: */ + /*/ <-- slash there */ + /* That shows up twice in a piece of 3rd-party + code i use. */ + /* And thus state3Col was introduced :/ */ + if(col!=state3Col+2){ + state = S_NONE; + elide = 0; + state3Col = -99; + } + } + } + break; + default: + assert(!"impossible!"); + break; + } + if('\n' == ch){ + ++line; + col = 0; + state3Col = -99; + } + } +} + +static void usage(char const *zAppName){ + fprintf(stderr, "Strips C- and C++-style comments from stdin and sends " + "the results to stdout.\n"); + fprintf(stderr, "Usage: %s [--keep-first|-k] < input > output\n", zAppName); +} + +int main( int argc, char const * const * argv ){ + int i; + for(i = 1; i < argc; ++i){ + char const * zArg = argv[i]; + while( '-'==*zArg ) ++zArg; + if( 0==strcmp(zArg,"k") + || 0==strcmp(zArg,"keep-first") ){ + ++App.keepFirst; + }else{ + usage(argv[0]); + return 1; + } + } + App.input = stdin; + App.output = stdout; + do_it_all(); + return App.rc ? 1 : 0; +} |