1 files changed, 94 insertions, 0 deletions
diff --git a/subst.c b/subst.c
new file mode 100644
index 0000000..75524ec
--- /dev/null
+++ b/subst.c
@@ -0,0 +1,94 @@
+#include <stddef.h>
+#include "jam.h"
+#include "regexp.h"
+#include "hash.h"
+
+#include "newstr.h"
+#include "lists.h"
+#include "parse.h"
+#include "compile.h"
+#include "frames.h"
+
+struct regex_entry
+{
+    const char* pattern;
+    regexp* regex;
+};
+typedef struct regex_entry regex_entry;
+
+static struct hash* regex_hash;
+
+regexp* regex_compile( const char* pattern )
+{
+    regex_entry entry, *e = &entry;
+    entry.pattern = pattern;
+
+    if ( !regex_hash )
+        regex_hash = hashinit(sizeof(regex_entry), "regex");
+
+    if ( hashenter( regex_hash, (HASHDATA **)&e ) )
+        e->regex = regcomp( (char*)pattern );
+
+    return e->regex;
+}
+
+LIST*
+builtin_subst(
+    PARSE    *parse,
+    FRAME      *frame )
+{
+  LIST* result = L0;
+  LIST* arg1 = lol_get( frame->args, 0 );
+
+  if ( arg1 && list_next(arg1) && list_next(list_next(arg1)) )
+  {
+
+      const char* source = arg1->string;
+      const char* pattern = list_next(arg1)->string;
+      regexp* repat = regex_compile( pattern );
+
+      if ( regexec( repat, (char*)source) )
+      {
+          LIST* subst = list_next(arg1);
+
+          while ((subst = list_next(subst)) != L0)
+          {
+# define BUFLEN 4096
+              char buf[BUFLEN + 1];
+              const char* in = subst->string;
+              char* out = buf;
+
+              for ( in = subst->string; *in && out < buf + BUFLEN; ++in )
+              {
+                  if ( *in == '\\' || *in == '$' )
+                  {
+                      ++in;
+                      if ( *in == 0 )
+                      {
+                          break;
+                      }
+                      else if ( *in >= '0' && *in <= '9' )
+                      {
+                          unsigned n = *in - '0';
+                          const size_t srclen = repat->endp[n] - repat->startp[n];
+                          const size_t remaining = buf + BUFLEN - out;
+                          const size_t len = srclen < remaining ? srclen : remaining;
+                          memcpy( out, repat->startp[n], len );
+                          out += len;
+                          continue;
+                      }
+                      /* fall through and copy the next character */
+                  }
+                  *out++ = *in;
+              }
+              *out = 0;
+
+              result = list_new( result, newstr( buf ) );
+#undef BUFLEN
+          }
+      }
+  }
+
+  return result;
+}
+