introduce grep output awareness

1 files changed, 54 insertions, 8 deletions

diff --git a/el.c b/el.c
index a1994b6..f615b5c 100644
--- a/el.c
+++ b/el.c
@@ -1,5 +1,5 @@
 /* Extract Lines
-   Usage: echo -x 10 2 7 100 | el data.txt
+   Usage: echo -x 10 2 7 100 | el -x data.txt
    extracts lines 16, 2, 7, 256 from the file data.txt
 */
 
@@ -25,12 +25,33 @@ static long indexfilled = 1;
 
 // If set, the stream of linenums specified calls
 // the first line number 0... *shiver*
-static int zerobased = 0;
+static int g_zerobased = 0;
+
+// If set, line numbers are prepended to each line
+// (the way grep does it, i.e. ^2342:<line>$)
+static int g_echolinenr = 0;
 
 // This tells us, whether we need to scan for hex
 // line numbers
 static char *g_scanfmodifier = "%i";
 
+// If user specifies some line numbers on command
+// line, store pointer here
+static char *g_immediatelinenums = (char *)0;
+
+// If input is guaranteed to come from "grep -n"
+// we will spare the user from "| cut -f 1 -d :"
+static int g_fromgrep = 0;
+static int g_fromgrepverbatim = 0;
+
+static int nextchar( void ) {
+  if( !g_immediatelinenums )
+    return getchar();
+  if( *g_immediatelinenums )
+    return *g_immediatelinenums++;
+  return EOF;
+}
+
 // scans the text file for the requested line
 // returns NULL, if line exceeds file's end
 // Note: we will not extend the index too early
@@ -118,10 +139,24 @@ static int acquire_lineno( int c ) {
   int inputindex = 0, lineno;
 
   while ( (c != EOF) && !isspace(c)) {
+    if( g_fromgrep && c == ':' ) {
+      if( g_echolinenr )
+        putchar( ':' );
+      while( ( ( c = nextchar() ) != EOF ) && ( c != '\n' ) )
+        if( g_fromgrepverbatim )
+          putchar(c);
+      if( g_fromgrepverbatim )
+        putchar( '\t' );
+      break;
+    }
+    if( g_echolinenr )
+      putchar( c );
     if( inputindex < 14 )
       input[inputindex++] = (char)c;
-    c = getchar();
+    c = nextchar();
   }
+  if( !g_fromgrep && g_echolinenr )
+    putchar( ':' );
 
   if( inputindex == 14 )
     return 0;
@@ -132,11 +167,11 @@ static int acquire_lineno( int c ) {
   if( sscanf( input, g_scanfmodifier, &lineno ) != 1 )
     return 0;
 
-  return lineno + zerobased;
+  return lineno + g_zerobased;
 }
 
 static void usage() {
-  fputs( "Usage: el [-0xh] filename < filenums\n", stderr);
+  fputs( "Usage: el [-0Ggnxh] [-i linenums] filename < linenum_file\n", stderr);
 }
 
 int main( int argc, char **argv ) {
@@ -144,14 +179,25 @@ int main( int argc, char **argv ) {
   MAP textfile = NULL;
   int c;
 
-  while ((c = getopt(argc, argv, ":0x")) != -1) {
+  while ((c = getopt(argc, argv, ":0i:gGnxh")) != -1) {
     switch (c) {
       case '0':
-        zerobased = 1;
+        g_zerobased = 1;
         break;
       case 'x':
         g_scanfmodifier = "%x";
         break;
+      case 'i':
+        g_immediatelinenums = optarg;
+        break;
+      case 'n':
+        g_echolinenr = 1;
+        break;
+      case 'G':
+        g_fromgrepverbatim = 1;
+      case 'g':
+        g_fromgrep = 1;
+        break;
       case 'h':
       case '?':
       default:
@@ -178,7 +224,7 @@ int main( int argc, char **argv ) {
   // First line starts at begin of file.
   index[0] = textfile->addr;
 
-  while( (c = getchar()) != EOF ) {
+  while( (c = nextchar()) != EOF ) {
     //         get linenumber, pass on eof test char
     long slen, lineno = acquire_lineno(c);
     unsigned char *line = scanforline( textfile, lineno, &slen );