From ab5153e97557791e2c12418ad3f53f53bed2a67a Mon Sep 17 00:00:00 2001
From: Jeffrey Armstrong <jeffrey.armstrong@approximatrix.com>
Date: Mon, 6 Jan 2014 20:44:03 -0500
Subject: Prism now supports diff versus the repository

---
 fcomp.c | 240 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 240 insertions(+)
 create mode 100644 fcomp.c

(limited to 'fcomp.c')

diff --git a/fcomp.c b/fcomp.c
new file mode 100644
index 0000000..41c5694
--- /dev/null
+++ b/fcomp.c
@@ -0,0 +1,240 @@
+/* fcomp.c:     
+
+   This code has been adapted from:
+   
+   Software Practice and Experience 
+   Vol 15, pp. 1025-1040, November 1985.
+   
+   "A File Comparison Program"
+   by Miller and Myers
+   http://tx0.org/7eq
+   
+   The modifications basically allow calling the diff routine
+   from a separate program, upping the max lines, and modernizing
+   some portions of the code.  Please don't ask me about the
+   theory involved, I do not understand it.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "prism.h"
+
+#define MAXLINES 15000
+#define ORIGIN MAXLINES
+#define INSERT 1
+#define DELETE 2
+
+struct edit {
+   struct edit *link;
+   int op;
+   int line1;
+   int line2;
+};
+
+static char **A, **B;
+
+static void fatal(const char *msg)
+{
+   printf("  ERR: %s\n",msg);
+}
+
+static void exceed(int d)
+{
+   printf("  ERR: the files differ in at least %d lines\n",d);
+}
+
+static int in_file(const char *filename, char **P)
+{
+char *buf, *save;
+FILE *fp, *fopen();
+int lines = 0;
+
+    if ((fp = fopen(filename,"r")) == NULL) 
+    {
+        fatal("cannot open file");
+        return PRET_READERROR;
+    }
+
+    buf = (char *)malloc(256*sizeof(char));
+    if(buf == NULL)
+        return PRET_ERROR;
+
+    while(fgets(buf,100,fp) != NULL) 
+    {
+        if (lines >= MAXLINES) {
+            fatal("file is to large for diff");
+            return PRET_ERROR;
+        }
+        
+        save = (char *)malloc((strlen(buf)+1)*sizeof(char));
+        if (save == NULL) {
+            fatal("not enough room to save the files");
+            return PRET_ERROR;
+        }
+        
+        P[lines++] = save;
+        strcpy(save, buf);
+    }
+    fclose(fp);
+    
+    free(buf);
+    return(lines);
+}
+
+static void put_scr(struct edit *start, const char *fname1, const char *fname2)
+{
+   struct edit *ep, *behind, *ahead, *a, *b;
+   int change;
+
+   ahead = start;
+   ep = NULL;
+   while (ahead != NULL) 
+   {
+      behind = ep;
+      ep = ahead;
+      ahead = ahead->link;
+      ep->link = behind;
+   }
+
+   while( ep != NULL  && 0 == 0) 
+   {
+      b = ep;
+      if (ep->op == INSERT)
+         //printf("Inserted after line %d:\n",ep->line1);
+         printf("line %s:%d || %s:%d\n", fname1, ep->line1, fname2, ep->line2);
+      else 
+      {
+         do 
+         {
+            a = b;
+            b = b->link;
+         } while (b!=NULL && b->op == DELETE && b->line1 == a->line1+1);
+
+         change = (b!=NULL && b->op == INSERT && b->line1 == a->line1);
+
+         if (a == ep)
+            printf("line %s:%d || %s:%d\n", fname1, ep->line1, fname2, ep->line2);
+            //printf("line %d:\n",ep->line1);
+         else
+            printf("line %s:%d-%d || %s:%d-%d\n", fname1, ep->line1, a->line1, fname2, ep->line2, a->line2);
+            //printf("lines %d-%d:\n",ep->line1,a->line1);
+
+         do 
+         {
+            printf("-%s",A[ep->line1-1]);
+            ep = ep->link;
+         } while (ep != b);
+
+         if (!change) {
+            printf("\n");
+            continue;
+         }
+      }
+      do 
+      {
+         printf("+%s",B[ep->line2-1]);
+         ep = ep->link;
+      } while (ep != NULL && ep->op == INSERT && ep->line1 == b->line1);
+      
+      printf("\n");
+   }
+}
+
+
+int compare_files(const char *fname1, const char *fname2)
+{
+   int   max_d,
+         m,
+         n,
+         lower,
+         upper,
+         d,
+         k,
+         row,
+         col;
+
+   int *last_d;
+   struct edit **script;
+
+   struct edit *new;
+
+   last_d = (int *)malloc((2*MAXLINES+1)*sizeof(int));
+   script = (struct edit **)malloc((2*MAXLINES+1)*sizeof(struct edit *));
+
+   A = (char **)malloc(MAXLINES*sizeof(char *));
+   B = (char **)malloc(MAXLINES*sizeof(char *));
+   if(A == NULL || B == NULL) return PRET_ERROR;
+   memset(A, 0, MAXLINES);
+   memset(B, 0, MAXLINES);
+
+   max_d = 2*MAXLINES;
+
+   m = in_file(fname1,A);
+   n = in_file(fname2,B);
+
+   for (row=0 ; row<m && row < n && strcmp(A[row],B[row]) == 0 ; ++row)
+      ;
+   last_d[ORIGIN] = row;
+   script[ORIGIN] = NULL;
+   lower = (row == m) ? ORIGIN + 1 : ORIGIN - 1;
+   upper = (row == n) ? ORIGIN - 1 : ORIGIN + 1;
+   if (lower > upper) 
+   {
+      printf("  the files are identical\n");
+      return PRET_OK;
+   }
+
+   for (d = 1 ; d <= max_d ; ++d) 
+   {
+      for ( k = lower ; k <= upper ; k +=2) 
+      {
+         new = (struct edit *) malloc(sizeof(struct edit));
+         if (new == NULL) {
+            exceed(d);
+            return PRET_ERROR;
+         }
+
+         if (k == ORIGIN-d || k != ORIGIN+d && last_d[k+1] >= last_d[k-1]) 
+         {
+            row = last_d[k+1]+1;
+            new->link = script[k+1];
+            new->op = DELETE;
+         } 
+         else 
+         {
+            row = last_d[k-1];
+            new->link = script[k-1];
+            new->op = INSERT;
+         }
+         new->line1 = row;
+         new->line2 = col = row + k - ORIGIN;
+         script[k] = new;
+
+         while(row < m && col < n && strcmp(A[row],B[col]) == 0) 
+         {
+            ++row;
+            ++col;
+         }
+         last_d[k] = row;
+
+         if (row == m && col == n)
+         {
+            put_scr(script[k], fname1, fname2);
+            return PRET_OK;
+         }
+         if (row == m)
+            lower = k+2;
+
+         if (col == n)
+            upper = k-2;
+      }
+      --lower;
+      ++upper;
+   }
+   
+   exceed(d);
+   return PRET_ERROR;
+}
+
-- 
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