Initial revision

diff --git a/linebyline.c b/linebyline.c
new file mode 100644 (file)
index 0000000..3e871ff
--- /dev/null
+++ b/linebyline.c
@@ -0,0 +1,156 @@
+/* filter.c -- filter lines for significance */
+#include <stdio.h>
+#include <sys/types.h>
+#include <regex.h>
+#include "shred.h"
+
+static char *c_patterns[] = {
+    /* Idioms that don't convey any meaning in isolation */
+    "return *\\(?[a-z]+\\)? *;", "return *\\(?-?[01]+\\)? *;",
+    "goto +[a-z]+;", "exit *\\([01]\\);",
+    /* Pragmas */
+    "/\\* *ARGSUSED *\\*/",
+    "/\\* *NOTREACHED *\\*/", 
+    "/\\* *FALL *THRO?UG?H? *\\*/",
+    /* Bare C keywords */
+
+    "[[:<:]]break[[:>:]]",  "[[:<:]]case[[:>:]]","[[:<:]]continue[[:>:]]", 
+    "[[:<:]]default[[:>:]]", "[[:<:]]do[[:>:]]", "[[:<:]]else[[:>:]]", 
+    "[[:<:]]enum[[:>:]]", "[[:<:]]if[[:>:]]", "[[:<:]]goto[[:>:]]",
+    "[[:<:]]return[[:>:]]", "[[:<:]]switch[[:>:]]", "[[:<:]]while[[:>:]]",
+    "[[:<:]]enum[[:>:]]", "[[:<:]]int[[:>:]]", "[[:<:]]long[[:>:]]",
+    "[[:<:]]short[[:>:]]", "[[:<:]]static[[:>:]]", "[[:<:]]struct[[:>:]]",
+    "[[:<:]]typedef[[:>:]]", "[[:<:]]union[[:>:]]", "[[:<:]]void[[:>:]]",
+    /* Preprocessor constructs */
+    "/* *define","# *endif","# *else","# *if[[:>:]]",
+    "# *ifdef[[:>:]]","# *ifndef[[:>:]]",
+    /* Comment delimiters with no content, and line continuation */
+    "/\\*+", "\\*+/", "\\*+", "^ *\\s*\\n", "\\\n",
+    /* Common preprocessor macros, not significant by themselves. */
+    "[[:<:]]ASSERT[[:>:]]", 
+    "[[:<:]]FALSE[[:>:]]", 
+    "[[:<:]]NULL[[:>:]]",
+    "[[:<:]]STATIC[[:>:]]", 
+    "[[:<:]]TRUE[[:>:]]",
+    /* Macro include lines are noise, too. */
+    "\\s*#include.*","#\\s*line.*",
+    /* Common error macros. */
+    "[[:<:]]EFAULT[[:>:]]",
+    "[[:<:]]EINVAL[[:>:]]",
+    "[[:<:]]ENOSYS[[:>:]]",
+};
+static regex_t c_regexps[sizeof(c_patterns)/sizeof(*c_patterns)];
+
+static char c_punct[] = {
+    /* Punctuation and whitespace */
+    '{', '}', '(', ')', '<', '>', '[', ']',
+    '^', '&', '|', '*', '?', '.', '+', 
+    ';', ':', '%', ',', '-', '/', '=', '!', 
+    '\n', '\t', '\v',
+};
+
+static char *shell_patterns[] = {
+    /* Idioms that don't convey any meaning in isolation */
+    "exit *[01];?",
+    /* Bare shell keywords */
+    "[[:<:]]break[[:>:]]", "[[:<:]]case[[:>:]]", "[[:<:]]done[[:>:]]", 
+    "[[:<:]]do[[:>:]]", "[[:<:]]else[[:>:]]", "[[:<:]]esac[[:>:]]",
+    "[[:<:]]fi[[:>:]]", "[[:<:]]if[[:>:]]", "[[:<:]]return[[:>:]]",
+    "[[:<:]]shift[[:>:]]", "[[:<:]]true[[:>:]]", "[[:<:]]while[[:>:]]", 
+    /* Blank comment */
+    "^#\n",
+};
+static regex_t shell_regexps[sizeof(shell_patterns)/sizeof(*shell_patterns)];
+
+static char shell_punct[] = {
+    /* Punctuation and whitespace */
+    ':', ';', '\n','\t', '\v',
+};
+
+void filter_init(void)
+/* initialize line filtering */
+{
+    int i;
+
+    for (i = 0; i < sizeof(c_patterns)/sizeof(*c_patterns); i++)
+       if (regcomp(c_regexps+i, c_patterns[i], REG_EXTENDED))
+       {
+           fprintf(stderr, "comparator: error while compiling %s\n",
+                   c_patterns[i]);
+           exit(1);
+       }
+    for (i = 0; i < sizeof(shell_patterns)/sizeof(*shell_patterns); i++)
+       if (regcomp(shell_regexps+i, shell_patterns[i], REG_EXTENDED))
+       {
+           fprintf(stderr, "comparator: error while compiling %s\n", 
+                   shell_patterns[i]);
+           exit(1);
+       }
+}
+
+static filtertype      active = none;
+static char *punct, **patterns;
+
+void filter_set(filtertype newfilter)
+{
+    active = newfilter;
+
+    if (newfilter == c)
+    {
+       patterns = c_patterns;
+       punct = c_punct;
+    }
+    else
+    {
+       patterns = shell_patterns;
+       punct = shell_punct;
+    }
+}
+
+int filter_pass(const char *line)
+{
+    if (active == none)
+       return(1);
+    else
+    {
+       char    buf[BUFSIZ][2];
+       int     changed, i = 0;
+
+       buf[0][0] = ' ';
+       strncpy(buf[0]+1, line, BUFSIZ-2);
+
+       while (changed)
+       {
+           char *s, *t, *sp, *tp;
+
+           s = buf[i]; t = buf[!i]; i ^= 1; changed = 0;
+
+           /* remove all punctuation */
+           for (sp = s, tp = t; *sp; sp++)
+               if (strchr(punct, *sp))
+                   changed++;
+               else
+                   *tp++ = *sp;
+           if (changed)
+               continue;
+
+           /* replace all regexps with the empty string */
+       }
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    char       buf[BUFSIZ];
+
+    filter_init();
+    filter_set(c);
+    while(fgets(buf, BUFSIZ, stdin))
+    {
+       if (filter_pass(buf))
+           fputs("!! ", stdout);
+       fputs(buf, stdout);
+    }
+}
+
+/* filter.c ends here */