1086 lines
31 KiB
C
1086 lines
31 KiB
C
/* Analyze file differences for GNU DIFF.
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Copyright (C) 1988, 1989, 1992, 1993, 1997 Free Software Foundation, Inc.
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This file is part of GNU DIFF.
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GNU DIFF is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU DIFF is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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*/
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/* The basic algorithm is described in:
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"An O(ND) Difference Algorithm and its Variations", Eugene Myers,
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Algorithmica Vol. 1 No. 2, 1986, pp. 251-266;
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see especially section 4.2, which describes the variation used below.
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Unless the --minimal option is specified, this code uses the TOO_EXPENSIVE
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heuristic, by Paul Eggert, to limit the cost to O(N**1.5 log N)
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at the price of producing suboptimal output for large inputs with
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many differences.
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The basic algorithm was independently discovered as described in:
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"Algorithms for Approximate String Matching", E. Ukkonen,
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Information and Control Vol. 64, 1985, pp. 100-118. */
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#include "diff.h"
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#include "cmpbuf.h"
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extern int no_discards;
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static int *xvec, *yvec; /* Vectors being compared. */
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static int *fdiag; /* Vector, indexed by diagonal, containing
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1 + the X coordinate of the point furthest
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along the given diagonal in the forward
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search of the edit matrix. */
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static int *bdiag; /* Vector, indexed by diagonal, containing
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the X coordinate of the point furthest
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along the given diagonal in the backward
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search of the edit matrix. */
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static int too_expensive; /* Edit scripts longer than this are too
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expensive to compute. */
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#define SNAKE_LIMIT 20 /* Snakes bigger than this are considered `big'. */
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struct partition
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{
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int xmid, ymid; /* Midpoints of this partition. */
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int lo_minimal; /* Nonzero if low half will be analyzed minimally. */
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int hi_minimal; /* Likewise for high half. */
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};
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static int diag PARAMS((int, int, int, int, int, struct partition *));
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static struct change *add_change PARAMS((int, int, int, int, struct change *));
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static struct change *build_reverse_script PARAMS((struct file_data const[]));
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static struct change *build_script PARAMS((struct file_data const[]));
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static void briefly_report PARAMS((int, struct file_data const[]));
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static void compareseq PARAMS((int, int, int, int, int));
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static void discard_confusing_lines PARAMS((struct file_data[]));
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static void shift_boundaries PARAMS((struct file_data[]));
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/* Find the midpoint of the shortest edit script for a specified
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portion of the two files.
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Scan from the beginnings of the files, and simultaneously from the ends,
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doing a breadth-first search through the space of edit-sequence.
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When the two searches meet, we have found the midpoint of the shortest
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edit sequence.
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If MINIMAL is nonzero, find the minimal edit script regardless
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of expense. Otherwise, if the search is too expensive, use
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heuristics to stop the search and report a suboptimal answer.
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Set PART->(XMID,YMID) to the midpoint (XMID,YMID). The diagonal number
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XMID - YMID equals the number of inserted lines minus the number
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of deleted lines (counting only lines before the midpoint).
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Return the approximate edit cost; this is the total number of
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lines inserted or deleted (counting only lines before the midpoint),
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unless a heuristic is used to terminate the search prematurely.
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Set PART->LEFT_MINIMAL to nonzero iff the minimal edit script for the
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left half of the partition is known; similarly for PART->RIGHT_MINIMAL.
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This function assumes that the first lines of the specified portions
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of the two files do not match, and likewise that the last lines do not
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match. The caller must trim matching lines from the beginning and end
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of the portions it is going to specify.
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If we return the "wrong" partitions,
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the worst this can do is cause suboptimal diff output.
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It cannot cause incorrect diff output. */
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static int
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diag (xoff, xlim, yoff, ylim, minimal, part)
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int xoff, xlim, yoff, ylim, minimal;
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struct partition *part;
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{
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int *const fd = fdiag; /* Give the compiler a chance. */
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int *const bd = bdiag; /* Additional help for the compiler. */
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int const *const xv = xvec; /* Still more help for the compiler. */
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int const *const yv = yvec; /* And more and more . . . */
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int const dmin = xoff - ylim; /* Minimum valid diagonal. */
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int const dmax = xlim - yoff; /* Maximum valid diagonal. */
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int const fmid = xoff - yoff; /* Center diagonal of top-down search. */
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int const bmid = xlim - ylim; /* Center diagonal of bottom-up search. */
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int fmin = fmid, fmax = fmid; /* Limits of top-down search. */
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int bmin = bmid, bmax = bmid; /* Limits of bottom-up search. */
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int c; /* Cost. */
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int odd = (fmid - bmid) & 1; /* True if southeast corner is on an odd
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diagonal with respect to the northwest. */
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fd[fmid] = xoff;
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bd[bmid] = xlim;
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for (c = 1;; ++c)
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{
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int d; /* Active diagonal. */
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int big_snake = 0;
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/* Extend the top-down search by an edit step in each diagonal. */
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fmin > dmin ? fd[--fmin - 1] = -1 : ++fmin;
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fmax < dmax ? fd[++fmax + 1] = -1 : --fmax;
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for (d = fmax; d >= fmin; d -= 2)
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{
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int x, y, oldx, tlo = fd[d - 1], thi = fd[d + 1];
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if (tlo >= thi)
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x = tlo + 1;
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else
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x = thi;
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oldx = x;
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y = x - d;
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while (x < xlim && y < ylim && xv[x] == yv[y])
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++x, ++y;
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if (x - oldx > SNAKE_LIMIT)
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big_snake = 1;
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fd[d] = x;
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if (odd && bmin <= d && d <= bmax && bd[d] <= x)
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{
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part->xmid = x;
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part->ymid = y;
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part->lo_minimal = part->hi_minimal = 1;
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return 2 * c - 1;
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}
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}
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/* Similarly extend the bottom-up search. */
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bmin > dmin ? bd[--bmin - 1] = INT_MAX : ++bmin;
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bmax < dmax ? bd[++bmax + 1] = INT_MAX : --bmax;
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for (d = bmax; d >= bmin; d -= 2)
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{
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int x, y, oldx, tlo = bd[d - 1], thi = bd[d + 1];
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if (tlo < thi)
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x = tlo;
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else
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x = thi - 1;
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oldx = x;
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y = x - d;
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while (x > xoff && y > yoff && xv[x - 1] == yv[y - 1])
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--x, --y;
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if (oldx - x > SNAKE_LIMIT)
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big_snake = 1;
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bd[d] = x;
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if (!odd && fmin <= d && d <= fmax && x <= fd[d])
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{
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part->xmid = x;
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part->ymid = y;
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part->lo_minimal = part->hi_minimal = 1;
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return 2 * c;
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}
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}
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if (minimal)
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continue;
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/* Heuristic: check occasionally for a diagonal that has made
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lots of progress compared with the edit distance.
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If we have any such, find the one that has made the most
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progress and return it as if it had succeeded.
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With this heuristic, for files with a constant small density
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of changes, the algorithm is linear in the file size. */
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if (c > 200 && big_snake && heuristic)
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{
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int best;
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best = 0;
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for (d = fmax; d >= fmin; d -= 2)
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{
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int dd = d - fmid;
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int x = fd[d];
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int y = x - d;
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int v = (x - xoff) * 2 - dd;
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if (v > 12 * (c + (dd < 0 ? -dd : dd)))
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{
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if (v > best
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&& xoff + SNAKE_LIMIT <= x && x < xlim
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&& yoff + SNAKE_LIMIT <= y && y < ylim)
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{
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/* We have a good enough best diagonal;
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now insist that it end with a significant snake. */
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int k;
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for (k = 1; xv[x - k] == yv[y - k]; k++)
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if (k == SNAKE_LIMIT)
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{
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best = v;
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part->xmid = x;
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part->ymid = y;
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break;
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}
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}
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}
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}
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if (best > 0)
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{
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part->lo_minimal = 1;
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part->hi_minimal = 0;
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return 2 * c - 1;
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}
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best = 0;
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for (d = bmax; d >= bmin; d -= 2)
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{
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int dd = d - bmid;
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int x = bd[d];
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int y = x - d;
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int v = (xlim - x) * 2 + dd;
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if (v > 12 * (c + (dd < 0 ? -dd : dd)))
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{
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if (v > best
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&& xoff < x && x <= xlim - SNAKE_LIMIT
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&& yoff < y && y <= ylim - SNAKE_LIMIT)
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{
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/* We have a good enough best diagonal;
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now insist that it end with a significant snake. */
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int k;
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for (k = 0; xv[x + k] == yv[y + k]; k++)
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if (k == SNAKE_LIMIT - 1)
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{
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best = v;
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part->xmid = x;
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part->ymid = y;
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break;
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}
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}
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}
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}
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if (best > 0)
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{
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part->lo_minimal = 0;
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part->hi_minimal = 1;
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return 2 * c - 1;
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}
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}
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/* Heuristic: if we've gone well beyond the call of duty,
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give up and report halfway between our best results so far. */
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if (c >= too_expensive)
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{
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int fxybest, fxbest;
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int bxybest, bxbest;
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fxbest = bxbest = 0; /* Pacify `gcc -Wall'. */
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/* Find forward diagonal that maximizes X + Y. */
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fxybest = -1;
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for (d = fmax; d >= fmin; d -= 2)
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{
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int x = min (fd[d], xlim);
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int y = x - d;
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if (ylim < y)
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x = ylim + d, y = ylim;
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if (fxybest < x + y)
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{
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fxybest = x + y;
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fxbest = x;
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}
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}
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/* Find backward diagonal that minimizes X + Y. */
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bxybest = INT_MAX;
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for (d = bmax; d >= bmin; d -= 2)
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{
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int x = max (xoff, bd[d]);
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int y = x - d;
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if (y < yoff)
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x = yoff + d, y = yoff;
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if (x + y < bxybest)
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{
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bxybest = x + y;
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bxbest = x;
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}
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}
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/* Use the better of the two diagonals. */
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if ((xlim + ylim) - bxybest < fxybest - (xoff + yoff))
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{
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part->xmid = fxbest;
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part->ymid = fxybest - fxbest;
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part->lo_minimal = 1;
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part->hi_minimal = 0;
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}
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else
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{
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part->xmid = bxbest;
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part->ymid = bxybest - bxbest;
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part->lo_minimal = 0;
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part->hi_minimal = 1;
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}
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return 2 * c - 1;
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}
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}
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}
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/* Compare in detail contiguous subsequences of the two files
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which are known, as a whole, to match each other.
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The results are recorded in the vectors files[N].changed_flag, by
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storing a 1 in the element for each line that is an insertion or deletion.
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The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
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Note that XLIM, YLIM are exclusive bounds.
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All line numbers are origin-0 and discarded lines are not counted.
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If MINIMAL is nonzero, find a minimal difference no matter how
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expensive it is. */
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static void
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compareseq (xoff, xlim, yoff, ylim, minimal)
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int xoff, xlim, yoff, ylim, minimal;
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{
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int * const xv = xvec; /* Help the compiler. */
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int * const yv = yvec;
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/* Slide down the bottom initial diagonal. */
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while (xoff < xlim && yoff < ylim && xv[xoff] == yv[yoff])
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++xoff, ++yoff;
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/* Slide up the top initial diagonal. */
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while (xlim > xoff && ylim > yoff && xv[xlim - 1] == yv[ylim - 1])
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--xlim, --ylim;
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/* Handle simple cases. */
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if (xoff == xlim)
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while (yoff < ylim)
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files[1].changed_flag[files[1].realindexes[yoff++]] = 1;
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else if (yoff == ylim)
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while (xoff < xlim)
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files[0].changed_flag[files[0].realindexes[xoff++]] = 1;
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else
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{
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int c;
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struct partition part;
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/* Find a point of correspondence in the middle of the files. */
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c = diag (xoff, xlim, yoff, ylim, minimal, &part);
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if (c == 1)
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{
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/* This should be impossible, because it implies that
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one of the two subsequences is empty,
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and that case was handled above without calling `diag'.
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Let's verify that this is true. */
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abort ();
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#if 0
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/* The two subsequences differ by a single insert or delete;
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record it and we are done. */
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if (part.xmid - part.ymid < xoff - yoff)
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files[1].changed_flag[files[1].realindexes[part.ymid - 1]] = 1;
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else
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files[0].changed_flag[files[0].realindexes[part.xmid]] = 1;
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#endif
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}
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||
else
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{
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/* Use the partitions to split this problem into subproblems. */
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compareseq (xoff, part.xmid, yoff, part.ymid, part.lo_minimal);
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compareseq (part.xmid, xlim, part.ymid, ylim, part.hi_minimal);
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}
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}
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}
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/* Discard lines from one file that have no matches in the other file.
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A line which is discarded will not be considered by the actual
|
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comparison algorithm; it will be as if that line were not in the file.
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The file's `realindexes' table maps virtual line numbers
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||
(which don't count the discarded lines) into real line numbers;
|
||
this is how the actual comparison algorithm produces results
|
||
that are comprehensible when the discarded lines are counted.
|
||
|
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When we discard a line, we also mark it as a deletion or insertion
|
||
so that it will be printed in the output. */
|
||
|
||
static void
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discard_confusing_lines (filevec)
|
||
struct file_data filevec[];
|
||
{
|
||
unsigned int f, i;
|
||
char *discarded[2];
|
||
int *equiv_count[2];
|
||
int *p;
|
||
|
||
/* Allocate our results. */
|
||
p = (int *) xmalloc ((filevec[0].buffered_lines + filevec[1].buffered_lines)
|
||
* (2 * sizeof (int)));
|
||
for (f = 0; f < 2; f++)
|
||
{
|
||
filevec[f].undiscarded = p; p += filevec[f].buffered_lines;
|
||
filevec[f].realindexes = p; p += filevec[f].buffered_lines;
|
||
}
|
||
|
||
/* Set up equiv_count[F][I] as the number of lines in file F
|
||
that fall in equivalence class I. */
|
||
|
||
p = (int *) xmalloc (filevec[0].equiv_max * (2 * sizeof (int)));
|
||
equiv_count[0] = p;
|
||
equiv_count[1] = p + filevec[0].equiv_max;
|
||
bzero (p, filevec[0].equiv_max * (2 * sizeof (int)));
|
||
|
||
for (i = 0; i < filevec[0].buffered_lines; ++i)
|
||
++equiv_count[0][filevec[0].equivs[i]];
|
||
for (i = 0; i < filevec[1].buffered_lines; ++i)
|
||
++equiv_count[1][filevec[1].equivs[i]];
|
||
|
||
/* Set up tables of which lines are going to be discarded. */
|
||
|
||
discarded[0] = xmalloc (sizeof (char)
|
||
* (filevec[0].buffered_lines
|
||
+ filevec[1].buffered_lines));
|
||
discarded[1] = discarded[0] + filevec[0].buffered_lines;
|
||
bzero (discarded[0], sizeof (char) * (filevec[0].buffered_lines
|
||
+ filevec[1].buffered_lines));
|
||
|
||
/* Mark to be discarded each line that matches no line of the other file.
|
||
If a line matches many lines, mark it as provisionally discardable. */
|
||
|
||
for (f = 0; f < 2; f++)
|
||
{
|
||
unsigned int end = filevec[f].buffered_lines;
|
||
char *discards = discarded[f];
|
||
int *counts = equiv_count[1 - f];
|
||
int *equivs = filevec[f].equivs;
|
||
unsigned int many = 5;
|
||
unsigned int tem = end / 64;
|
||
|
||
/* Multiply MANY by approximate square root of number of lines.
|
||
That is the threshold for provisionally discardable lines. */
|
||
while ((tem = tem >> 2) > 0)
|
||
many *= 2;
|
||
|
||
for (i = 0; i < end; i++)
|
||
{
|
||
int nmatch;
|
||
if (equivs[i] == 0)
|
||
continue;
|
||
nmatch = counts[equivs[i]];
|
||
if (nmatch == 0)
|
||
discards[i] = 1;
|
||
else if (nmatch > many)
|
||
discards[i] = 2;
|
||
}
|
||
}
|
||
|
||
/* Don't really discard the provisional lines except when they occur
|
||
in a run of discardables, with nonprovisionals at the beginning
|
||
and end. */
|
||
|
||
for (f = 0; f < 2; f++)
|
||
{
|
||
unsigned int end = filevec[f].buffered_lines;
|
||
register char *discards = discarded[f];
|
||
|
||
for (i = 0; i < end; i++)
|
||
{
|
||
/* Cancel provisional discards not in middle of run of discards. */
|
||
if (discards[i] == 2)
|
||
discards[i] = 0;
|
||
else if (discards[i] != 0)
|
||
{
|
||
/* We have found a nonprovisional discard. */
|
||
register int j;
|
||
unsigned int length;
|
||
unsigned int provisional = 0;
|
||
|
||
/* Find end of this run of discardable lines.
|
||
Count how many are provisionally discardable. */
|
||
for (j = i; j < end; j++)
|
||
{
|
||
if (discards[j] == 0)
|
||
break;
|
||
if (discards[j] == 2)
|
||
++provisional;
|
||
}
|
||
|
||
/* Cancel provisional discards at end, and shrink the run. */
|
||
while (j > i && discards[j - 1] == 2)
|
||
discards[--j] = 0, --provisional;
|
||
|
||
/* Now we have the length of a run of discardable lines
|
||
whose first and last are not provisional. */
|
||
length = j - i;
|
||
|
||
/* If 1/4 of the lines in the run are provisional,
|
||
cancel discarding of all provisional lines in the run. */
|
||
if (provisional * 4 > length)
|
||
{
|
||
while (j > i)
|
||
if (discards[--j] == 2)
|
||
discards[j] = 0;
|
||
}
|
||
else
|
||
{
|
||
register unsigned int consec;
|
||
unsigned int minimum = 1;
|
||
unsigned int tem = length / 4;
|
||
|
||
/* MINIMUM is approximate square root of LENGTH/4.
|
||
A subrun of two or more provisionals can stand
|
||
when LENGTH is at least 16.
|
||
A subrun of 4 or more can stand when LENGTH >= 64. */
|
||
while ((tem = tem >> 2) > 0)
|
||
minimum *= 2;
|
||
minimum++;
|
||
|
||
/* Cancel any subrun of MINIMUM or more provisionals
|
||
within the larger run. */
|
||
for (j = 0, consec = 0; j < length; j++)
|
||
if (discards[i + j] != 2)
|
||
consec = 0;
|
||
else if (minimum == ++consec)
|
||
/* Back up to start of subrun, to cancel it all. */
|
||
j -= consec;
|
||
else if (minimum < consec)
|
||
discards[i + j] = 0;
|
||
|
||
/* Scan from beginning of run
|
||
until we find 3 or more nonprovisionals in a row
|
||
or until the first nonprovisional at least 8 lines in.
|
||
Until that point, cancel any provisionals. */
|
||
for (j = 0, consec = 0; j < length; j++)
|
||
{
|
||
if (j >= 8 && discards[i + j] == 1)
|
||
break;
|
||
if (discards[i + j] == 2)
|
||
consec = 0, discards[i + j] = 0;
|
||
else if (discards[i + j] == 0)
|
||
consec = 0;
|
||
else
|
||
consec++;
|
||
if (consec == 3)
|
||
break;
|
||
}
|
||
|
||
/* I advances to the last line of the run. */
|
||
i += length - 1;
|
||
|
||
/* Same thing, from end. */
|
||
for (j = 0, consec = 0; j < length; j++)
|
||
{
|
||
if (j >= 8 && discards[i - j] == 1)
|
||
break;
|
||
if (discards[i - j] == 2)
|
||
consec = 0, discards[i - j] = 0;
|
||
else if (discards[i - j] == 0)
|
||
consec = 0;
|
||
else
|
||
consec++;
|
||
if (consec == 3)
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Actually discard the lines. */
|
||
for (f = 0; f < 2; f++)
|
||
{
|
||
char *discards = discarded[f];
|
||
unsigned int end = filevec[f].buffered_lines;
|
||
unsigned int j = 0;
|
||
for (i = 0; i < end; ++i)
|
||
if (no_discards || discards[i] == 0)
|
||
{
|
||
filevec[f].undiscarded[j] = filevec[f].equivs[i];
|
||
filevec[f].realindexes[j++] = i;
|
||
}
|
||
else
|
||
filevec[f].changed_flag[i] = 1;
|
||
filevec[f].nondiscarded_lines = j;
|
||
}
|
||
|
||
free (discarded[0]);
|
||
free (equiv_count[0]);
|
||
}
|
||
|
||
/* Adjust inserts/deletes of identical lines to join changes
|
||
as much as possible.
|
||
|
||
We do something when a run of changed lines include a
|
||
line at one end and have an excluded, identical line at the other.
|
||
We are free to choose which identical line is included.
|
||
`compareseq' usually chooses the one at the beginning,
|
||
but usually it is cleaner to consider the following identical line
|
||
to be the "change". */
|
||
|
||
int inhibit;
|
||
|
||
static void
|
||
shift_boundaries (filevec)
|
||
struct file_data filevec[];
|
||
{
|
||
int f;
|
||
int inhibit_hunk_merge = horizon_lines != context;
|
||
|
||
for (f = 0; f < 2; f++)
|
||
{
|
||
char *changed = filevec[f].changed_flag;
|
||
char const *other_changed = filevec[1-f].changed_flag;
|
||
int const *equivs = filevec[f].equivs;
|
||
int i = 0;
|
||
int j = 0;
|
||
int i_end = filevec[f].buffered_lines;
|
||
|
||
while (1)
|
||
{
|
||
int runlength, start, corresponding;
|
||
|
||
/* Scan forwards to find beginning of another run of changes.
|
||
Also keep track of the corresponding point in the other file. */
|
||
|
||
while (i < i_end && changed[i] == 0)
|
||
{
|
||
while (other_changed[j++])
|
||
continue;
|
||
i++;
|
||
}
|
||
|
||
if (i == i_end)
|
||
break;
|
||
|
||
start = i;
|
||
|
||
/* Find the end of this run of changes. */
|
||
|
||
while (changed[++i])
|
||
continue;
|
||
while (other_changed[j])
|
||
j++;
|
||
|
||
do
|
||
{
|
||
/* Record the length of this run of changes, so that
|
||
we can later determine whether the run has grown. */
|
||
runlength = i - start;
|
||
|
||
if (! inhibit_hunk_merge)
|
||
{
|
||
/* Move the changed region back, so long as the
|
||
previous unchanged line matches the last changed one.
|
||
This merges with previous changed regions. */
|
||
|
||
while (start && equivs[start - 1] == equivs[i - 1])
|
||
{
|
||
changed[--start] = 1;
|
||
changed[--i] = 0;
|
||
while (changed[start - 1])
|
||
start--;
|
||
while (other_changed[--j])
|
||
continue;
|
||
}
|
||
}
|
||
|
||
/* Set CORRESPONDING to the end of the changed run, at the last
|
||
point where it corresponds to a changed run in the other file.
|
||
CORRESPONDING == I_END means no such point has been found. */
|
||
corresponding = other_changed[j - 1] ? i : i_end;
|
||
|
||
/* Shift the changed region forward, so long as the
|
||
first changed line matches the following unchanged one,
|
||
but if INHIBIT_HUNK_MERGE is 1 do not shift if
|
||
this would merge with another changed region.
|
||
Do this second, so that if there are no merges,
|
||
the changed region is moved forward as far as possible. */
|
||
|
||
while (i != i_end && equivs[start] == equivs[i]
|
||
&& ! (inhibit_hunk_merge & other_changed[j + 1]))
|
||
{
|
||
changed[start++] = 0;
|
||
changed[i++] = 1;
|
||
while (changed[i])
|
||
i++;
|
||
while (other_changed[++j])
|
||
corresponding = i;
|
||
}
|
||
}
|
||
while (runlength != i - start);
|
||
|
||
/* If possible, move the fully-merged run of changes
|
||
back to a corresponding run in the other file. */
|
||
|
||
while (corresponding < i)
|
||
{
|
||
changed[--start] = 1;
|
||
changed[--i] = 0;
|
||
while (other_changed[--j])
|
||
continue;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Cons an additional entry onto the front of an edit script OLD.
|
||
LINE0 and LINE1 are the first affected lines in the two files (origin 0).
|
||
DELETED is the number of lines deleted here from file 0.
|
||
INSERTED is the number of lines inserted here in file 1.
|
||
|
||
If DELETED is 0 then LINE0 is the number of the line before
|
||
which the insertion was done; vice versa for INSERTED and LINE1. */
|
||
|
||
static struct change *
|
||
add_change (line0, line1, deleted, inserted, old)
|
||
int line0, line1, deleted, inserted;
|
||
struct change *old;
|
||
{
|
||
struct change *new = (struct change *) xmalloc (sizeof (struct change));
|
||
|
||
new->line0 = line0;
|
||
new->line1 = line1;
|
||
new->inserted = inserted;
|
||
new->deleted = deleted;
|
||
new->link = old;
|
||
return new;
|
||
}
|
||
|
||
/* Scan the tables of which lines are inserted and deleted,
|
||
producing an edit script in reverse order. */
|
||
|
||
static struct change *
|
||
build_reverse_script (filevec)
|
||
struct file_data const filevec[];
|
||
{
|
||
struct change *script = 0;
|
||
char *changed0 = filevec[0].changed_flag;
|
||
char *changed1 = filevec[1].changed_flag;
|
||
int len0 = filevec[0].buffered_lines;
|
||
int len1 = filevec[1].buffered_lines;
|
||
|
||
/* Note that changedN[len0] does exist, and contains 0. */
|
||
|
||
int i0 = 0, i1 = 0;
|
||
|
||
while (i0 < len0 || i1 < len1)
|
||
{
|
||
if (changed0[i0] || changed1[i1])
|
||
{
|
||
int line0 = i0, line1 = i1;
|
||
|
||
/* Find # lines changed here in each file. */
|
||
while (changed0[i0]) ++i0;
|
||
while (changed1[i1]) ++i1;
|
||
|
||
/* Record this change. */
|
||
script = add_change (line0, line1, i0 - line0, i1 - line1, script);
|
||
}
|
||
|
||
/* We have reached lines in the two files that match each other. */
|
||
i0++, i1++;
|
||
}
|
||
|
||
return script;
|
||
}
|
||
|
||
/* Scan the tables of which lines are inserted and deleted,
|
||
producing an edit script in forward order. */
|
||
|
||
static struct change *
|
||
build_script (filevec)
|
||
struct file_data const filevec[];
|
||
{
|
||
struct change *script = 0;
|
||
char *changed0 = filevec[0].changed_flag;
|
||
char *changed1 = filevec[1].changed_flag;
|
||
int i0 = filevec[0].buffered_lines, i1 = filevec[1].buffered_lines;
|
||
|
||
/* Note that changedN[-1] does exist, and contains 0. */
|
||
|
||
while (i0 >= 0 || i1 >= 0)
|
||
{
|
||
if (changed0[i0 - 1] || changed1[i1 - 1])
|
||
{
|
||
int line0 = i0, line1 = i1;
|
||
|
||
/* Find # lines changed here in each file. */
|
||
while (changed0[i0 - 1]) --i0;
|
||
while (changed1[i1 - 1]) --i1;
|
||
|
||
/* Record this change. */
|
||
script = add_change (i0, i1, line0 - i0, line1 - i1, script);
|
||
}
|
||
|
||
/* We have reached lines in the two files that match each other. */
|
||
i0--, i1--;
|
||
}
|
||
|
||
return script;
|
||
}
|
||
|
||
/* If CHANGES, briefly report that two files differed. */
|
||
static void
|
||
briefly_report (changes, filevec)
|
||
int changes;
|
||
struct file_data const filevec[];
|
||
{
|
||
if (changes)
|
||
message (no_details_flag ? "Files %s and %s differ\n"
|
||
: "Binary files %s and %s differ\n",
|
||
filevec[0].name, filevec[1].name);
|
||
}
|
||
|
||
/* Report the differences of two files. DEPTH is the current directory
|
||
depth. */
|
||
int
|
||
diff_2_files (filevec, depth)
|
||
struct file_data filevec[];
|
||
int depth;
|
||
{
|
||
int diags;
|
||
int i;
|
||
struct change *e, *p;
|
||
struct change *script;
|
||
int changes;
|
||
|
||
|
||
/* If we have detected that either file is binary,
|
||
compare the two files as binary. This can happen
|
||
only when the first chunk is read.
|
||
Also, --brief without any --ignore-* options means
|
||
we can speed things up by treating the files as binary. */
|
||
|
||
if (read_files (filevec, no_details_flag & ~ignore_some_changes))
|
||
{
|
||
/* Files with different lengths must be different. */
|
||
if (filevec[0].stat.st_size != filevec[1].stat.st_size
|
||
&& (filevec[0].desc < 0 || S_ISREG (filevec[0].stat.st_mode))
|
||
&& (filevec[1].desc < 0 || S_ISREG (filevec[1].stat.st_mode)))
|
||
changes = 1;
|
||
|
||
/* Standard input equals itself. */
|
||
else if (filevec[0].desc == filevec[1].desc)
|
||
changes = 0;
|
||
|
||
else
|
||
/* Scan both files, a buffer at a time, looking for a difference. */
|
||
{
|
||
/* Allocate same-sized buffers for both files. */
|
||
size_t buffer_size = buffer_lcm (STAT_BLOCKSIZE (filevec[0].stat),
|
||
STAT_BLOCKSIZE (filevec[1].stat));
|
||
for (i = 0; i < 2; i++)
|
||
filevec[i].buffer = xrealloc (filevec[i].buffer, buffer_size);
|
||
|
||
for (;; filevec[0].buffered_chars = filevec[1].buffered_chars = 0)
|
||
{
|
||
/* Read a buffer's worth from both files. */
|
||
for (i = 0; i < 2; i++)
|
||
if (0 <= filevec[i].desc)
|
||
while (filevec[i].buffered_chars != buffer_size)
|
||
{
|
||
int r = read (filevec[i].desc,
|
||
filevec[i].buffer
|
||
+ filevec[i].buffered_chars,
|
||
buffer_size - filevec[i].buffered_chars);
|
||
if (r == 0)
|
||
break;
|
||
if (r < 0)
|
||
pfatal_with_name (filevec[i].name);
|
||
filevec[i].buffered_chars += r;
|
||
}
|
||
|
||
/* If the buffers differ, the files differ. */
|
||
if (filevec[0].buffered_chars != filevec[1].buffered_chars
|
||
|| (filevec[0].buffered_chars != 0
|
||
&& memcmp (filevec[0].buffer,
|
||
filevec[1].buffer,
|
||
filevec[0].buffered_chars) != 0))
|
||
{
|
||
changes = 1;
|
||
break;
|
||
}
|
||
|
||
/* If we reach end of file, the files are the same. */
|
||
if (filevec[0].buffered_chars != buffer_size)
|
||
{
|
||
changes = 0;
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
|
||
briefly_report (changes, filevec);
|
||
}
|
||
else
|
||
{
|
||
/* Allocate vectors for the results of comparison:
|
||
a flag for each line of each file, saying whether that line
|
||
is an insertion or deletion.
|
||
Allocate an extra element, always zero, at each end of each vector. */
|
||
|
||
size_t s = filevec[0].buffered_lines + filevec[1].buffered_lines + 4;
|
||
filevec[0].changed_flag = xmalloc (s);
|
||
bzero (filevec[0].changed_flag, s);
|
||
filevec[0].changed_flag++;
|
||
filevec[1].changed_flag = filevec[0].changed_flag
|
||
+ filevec[0].buffered_lines + 2;
|
||
|
||
/* Some lines are obviously insertions or deletions
|
||
because they don't match anything. Detect them now, and
|
||
avoid even thinking about them in the main comparison algorithm. */
|
||
|
||
discard_confusing_lines (filevec);
|
||
|
||
/* Now do the main comparison algorithm, considering just the
|
||
undiscarded lines. */
|
||
|
||
xvec = filevec[0].undiscarded;
|
||
yvec = filevec[1].undiscarded;
|
||
diags = filevec[0].nondiscarded_lines + filevec[1].nondiscarded_lines + 3;
|
||
fdiag = (int *) xmalloc (diags * (2 * sizeof (int)));
|
||
bdiag = fdiag + diags;
|
||
fdiag += filevec[1].nondiscarded_lines + 1;
|
||
bdiag += filevec[1].nondiscarded_lines + 1;
|
||
|
||
/* Set TOO_EXPENSIVE to be approximate square root of input size,
|
||
bounded below by 256. */
|
||
too_expensive = 1;
|
||
for (i = filevec[0].nondiscarded_lines + filevec[1].nondiscarded_lines;
|
||
i != 0; i >>= 2)
|
||
too_expensive <<= 1;
|
||
too_expensive = max (256, too_expensive);
|
||
|
||
files[0] = filevec[0];
|
||
files[1] = filevec[1];
|
||
|
||
compareseq (0, filevec[0].nondiscarded_lines,
|
||
0, filevec[1].nondiscarded_lines, no_discards);
|
||
|
||
free (fdiag - (filevec[1].nondiscarded_lines + 1));
|
||
|
||
/* Modify the results slightly to make them prettier
|
||
in cases where that can validly be done. */
|
||
|
||
shift_boundaries (filevec);
|
||
|
||
/* Get the results of comparison in the form of a chain
|
||
of `struct change's -- an edit script. */
|
||
|
||
if (output_style == OUTPUT_ED)
|
||
script = build_reverse_script (filevec);
|
||
else
|
||
script = build_script (filevec);
|
||
|
||
/* Set CHANGES if we had any diffs.
|
||
If some changes are ignored, we must scan the script to decide. */
|
||
if (ignore_blank_lines_flag || ignore_regexp_list)
|
||
{
|
||
struct change *next = script;
|
||
changes = 0;
|
||
|
||
while (next && changes == 0)
|
||
{
|
||
struct change *this, *end;
|
||
int first0, last0, first1, last1, deletes, inserts;
|
||
|
||
/* Find a set of changes that belong together. */
|
||
this = next;
|
||
end = find_change (next);
|
||
|
||
/* Disconnect them from the rest of the changes, making them
|
||
a hunk, and remember the rest for next iteration. */
|
||
next = end->link;
|
||
end->link = 0;
|
||
|
||
/* Determine whether this hunk is really a difference. */
|
||
analyze_hunk (this, &first0, &last0, &first1, &last1,
|
||
&deletes, &inserts);
|
||
|
||
/* Reconnect the script so it will all be freed properly. */
|
||
end->link = next;
|
||
|
||
if (deletes || inserts)
|
||
changes = 1;
|
||
}
|
||
}
|
||
else
|
||
changes = (script != 0);
|
||
|
||
if (no_details_flag)
|
||
briefly_report (changes, filevec);
|
||
else
|
||
{
|
||
if (changes || ! no_diff_means_no_output)
|
||
{
|
||
/* Record info for starting up output,
|
||
to be used if and when we have some output to print. */
|
||
setup_output (files[0].name, files[1].name, depth);
|
||
|
||
switch (output_style)
|
||
{
|
||
case OUTPUT_CONTEXT:
|
||
print_context_script (script, 0);
|
||
break;
|
||
|
||
case OUTPUT_UNIFIED:
|
||
print_context_script (script, 1);
|
||
break;
|
||
|
||
case OUTPUT_ED:
|
||
print_ed_script (script);
|
||
break;
|
||
|
||
case OUTPUT_FORWARD_ED:
|
||
pr_forward_ed_script (script);
|
||
break;
|
||
|
||
case OUTPUT_RCS:
|
||
print_rcs_script (script);
|
||
break;
|
||
|
||
case OUTPUT_NORMAL:
|
||
print_normal_script (script);
|
||
break;
|
||
|
||
case OUTPUT_IFDEF:
|
||
print_ifdef_script (script);
|
||
break;
|
||
|
||
case OUTPUT_SDIFF:
|
||
print_sdiff_script (script);
|
||
}
|
||
|
||
finish_output ();
|
||
}
|
||
}
|
||
|
||
free (filevec[0].undiscarded);
|
||
|
||
free (filevec[0].changed_flag - 1);
|
||
|
||
for (i = 1; i >= 0; --i)
|
||
free (filevec[i].equivs);
|
||
|
||
for (i = 0; i < 2; ++i)
|
||
free (filevec[i].linbuf + filevec[i].linbuf_base);
|
||
|
||
for (e = script; e; e = p)
|
||
{
|
||
p = e->link;
|
||
free (e);
|
||
}
|
||
|
||
if (! ROBUST_OUTPUT_STYLE (output_style))
|
||
for (i = 0; i < 2; ++i)
|
||
if (filevec[i].missing_newline)
|
||
{
|
||
diff_error ("No newline at end of file %s", filevec[i].name, "");
|
||
changes = 2;
|
||
}
|
||
}
|
||
|
||
if (filevec[0].buffer != filevec[1].buffer)
|
||
free (filevec[0].buffer);
|
||
free (filevec[1].buffer);
|
||
|
||
return changes;
|
||
}
|