thodg/got/lib/diff_output_unidiff.c

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• Hash : f3c44083
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  Date : 2020-11-14T16:39:35
  

  sync files from diff.git fe6d58fb52ea8d1041a8eb65e28a04816df67c08

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• lib/diff_output_unidiff.c

• /* Produce a unidiff output from a diff_result. */
  /*
   * Copyright (c) 2020 Neels Hofmeyr <neels@hofmeyr.de>
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include <errno.h>
  #include <stdbool.h>
  #include <stdint.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <assert.h>
  
  #include <arraylist.h>
  #include <diff_main.h>
  #include <diff_output.h>
  
  #include "diff_internal.h"
  #include "diff_debug.h"
  
  bool
  diff_chunk_context_empty(const struct diff_chunk_context *cc)
  {
  	return diff_range_empty(&cc->chunk);
  }
  
  int
  diff_chunk_get_left_start(const struct diff_chunk *c,
      const struct diff_result *r, int context_lines)
  {
  	int left_start = diff_atom_root_idx(r->left, c->left_start);
  	return MAX(0, left_start - context_lines);
  }
  
  int
  diff_chunk_get_left_end(const struct diff_chunk *c,
      const struct diff_result *r, int context_lines)
  {
  	int left_start = diff_chunk_get_left_start(c, r, 0);
  	return MIN(r->left->atoms.len,
  	    left_start + c->left_count + context_lines);
  }
  
  int
  diff_chunk_get_right_start(const struct diff_chunk *c,
      const struct diff_result *r, int context_lines)
  {
  	int right_start = diff_atom_root_idx(r->right, c->right_start);
  	return MAX(0, right_start - context_lines);
  }
  
  int
  diff_chunk_get_right_end(const struct diff_chunk *c,
      const struct diff_result *r, int context_lines)
  {
  	int right_start = diff_chunk_get_right_start(c, r, 0);
  	return MIN(r->right->atoms.len,
  	    right_start + c->right_count + context_lines);
  }
  
  struct diff_chunk *
  diff_chunk_get(const struct diff_result *r, int chunk_idx)
  {
  	return &r->chunks.head[chunk_idx];
  }
  
  int
  diff_chunk_get_left_count(struct diff_chunk *c)
  {
  	return c->left_count;
  }
  
  int
  diff_chunk_get_right_count(struct diff_chunk *c)
  {
  	return c->right_count;
  }
  
  void
  diff_chunk_context_get(struct diff_chunk_context *cc, const struct diff_result *r,
  		  int chunk_idx, int context_lines)
  {
  	const struct diff_chunk *c = &r->chunks.head[chunk_idx];
  	int left_start = diff_chunk_get_left_start(c, r, context_lines);
  	int left_end = diff_chunk_get_left_end(c, r, context_lines);
  	int right_start = diff_chunk_get_right_start(c, r, context_lines);
  	int right_end = diff_chunk_get_right_end(c, r,  context_lines);
  
  	*cc = (struct diff_chunk_context){
  		.chunk = {
  			.start = chunk_idx,
  			.end = chunk_idx + 1,
  		},
  		.left = {
  			.start = left_start,
  			.end = left_end,
  		},
  		.right = {
  			.start = right_start,
  			.end = right_end,
  		},
  	};
  }
  
  bool
  diff_chunk_contexts_touch(const struct diff_chunk_context *cc,
  			  const struct diff_chunk_context *other)
  {
  	return diff_ranges_touch(&cc->chunk, &other->chunk)
  		|| diff_ranges_touch(&cc->left, &other->left)
  		|| diff_ranges_touch(&cc->right, &other->right);
  }
  
  void
  diff_chunk_contexts_merge(struct diff_chunk_context *cc,
  			  const struct diff_chunk_context *other)
  {
  	diff_ranges_merge(&cc->chunk, &other->chunk);
  	diff_ranges_merge(&cc->left, &other->left);
  	diff_ranges_merge(&cc->right, &other->right);
  }
  
  void
  diff_chunk_context_load_change(struct diff_chunk_context *cc,
  			       int *nchunks_used,
  			       struct diff_result *result,
  			       int start_chunk_idx,
  			       int context_lines)
  {
  	int i;
  	int seen_minus = 0, seen_plus = 0;
  
  	if (nchunks_used)
  		*nchunks_used = 0;
  
  	for (i = start_chunk_idx; i < result->chunks.len; i++) {
  		struct diff_chunk *chunk = &result->chunks.head[i];
  		enum diff_chunk_type t = diff_chunk_type(chunk);
  		struct diff_chunk_context next;
  
  		if (t != CHUNK_MINUS && t != CHUNK_PLUS) {
  			if (nchunks_used)
  				(*nchunks_used)++;
  			if (seen_minus || seen_plus)
  				break;
  			else
  				continue;
  		} else if (t == CHUNK_MINUS)
  			seen_minus = 1;
  		else if (t == CHUNK_PLUS)
  			seen_plus = 1;
  
  		if (diff_chunk_context_empty(cc)) {
  			/* Note down the start point, any number of subsequent
  			 * chunks may be joined up to this chunk by being
  			 * directly adjacent. */
  			diff_chunk_context_get(cc, result, i, context_lines);
  			if (nchunks_used)
  				(*nchunks_used)++;
  			continue;
  		}
  
  		/* There already is a previous chunk noted down for being
  		 * printed. Does it join up with this one? */
  		diff_chunk_context_get(&next, result, i, context_lines);
  
  		if (diff_chunk_contexts_touch(cc, &next)) {
  			/* This next context touches or overlaps the previous
  			 * one, join. */
  			diff_chunk_contexts_merge(cc, &next);
  			if (nchunks_used)
  				(*nchunks_used)++;
  			continue;
  		} else
  			break;
  	}
  }
  
  struct diff_output_unidiff_state {
  	bool header_printed;
  };
  
  struct diff_output_unidiff_state *
  diff_output_unidiff_state_alloc(void)
  {
  	struct diff_output_unidiff_state *state;
  
  	state = calloc(1, sizeof(struct diff_output_unidiff_state));
  	if (state != NULL)
  		diff_output_unidiff_state_reset(state);
  	return state;
  }
  
  void
  diff_output_unidiff_state_reset(struct diff_output_unidiff_state *state)
  {
  	state->header_printed = false;
  }
  
  void
  diff_output_unidiff_state_free(struct diff_output_unidiff_state *state)
  {
  	free(state);
  }
  
  static int
  output_unidiff_chunk(struct diff_output_info *outinfo, FILE *dest,
  		     struct diff_output_unidiff_state *state,
  		     const struct diff_input_info *info,
  		     const struct diff_result *result,
  		     bool print_header, bool show_function_prototypes,
  		     const struct diff_chunk_context *cc)
  {
  	int rc, left_start, left_len, right_start, right_len;
  	off_t outoff = 0, *offp;
  	char *prototype = NULL;
  
  	if (diff_range_empty(&cc->left) && diff_range_empty(&cc->right))
  		return DIFF_RC_OK;
  
  	if (outinfo && outinfo->line_offsets.len > 0) {
  		unsigned int idx = outinfo->line_offsets.len - 1;
  		outoff = outinfo->line_offsets.head[idx];
  	}
  
  	if (print_header && !(state->header_printed)) {
  		rc = fprintf(dest, "--- %s\n", info->left_path ? : "a");
  		if (rc < 0)
  			return errno;
  		if (outinfo) {
  			ARRAYLIST_ADD(offp, outinfo->line_offsets);
  			if (offp == NULL)
  				return ENOMEM;
  			outoff += rc;
  			*offp = outoff;
  
  		}
  		rc = fprintf(dest, "+++ %s\n", info->right_path ? : "b");
  		if (rc < 0)
  			return errno;
  		if (outinfo) {
  			ARRAYLIST_ADD(offp, outinfo->line_offsets);
  			if (offp == NULL)
  				return ENOMEM;
  			outoff += rc;
  			*offp = outoff;
  
  		}
  		state->header_printed = true;
  	}
  
  	left_len = cc->left.end - cc->left.start;
  	if (result->left->atoms.len == 0)
  		left_start = 0;
  	else if (left_len == 0 && cc->left.start > 0)
  		left_start = cc->left.start;
  	else
  		left_start = cc->left.start + 1;
  
  	right_len = cc->right.end - cc->right.start;
  	if (result->right->atoms.len == 0)
  		right_start = 0;
  	else if (right_len == 0 && cc->right.start > 0)
  		right_start = cc->right.start;
  	else
  		right_start = cc->right.start + 1;
  
  	if (show_function_prototypes) {
  		rc = diff_output_match_function_prototype(&prototype,
  		    result, cc);
  		if (rc)
  			return rc;
  	}
  
  	if (left_len == 1 && right_len == 1) {
  		rc = fprintf(dest, "@@ -%d +%d @@%s%s\n",
  			left_start, right_start,
  			prototype ? " " : "",
  			prototype ? : "");
  	} else if (left_len == 1 && right_len != 1) {
  		rc = fprintf(dest, "@@ -%d +%d,%d @@%s%s\n",
  			left_start, right_start, right_len,
  			prototype ? " " : "",
  			prototype ? : "");
  	} else if (left_len != 1 && right_len == 1) {
  		rc = fprintf(dest, "@@ -%d,%d +%d @@%s%s\n",
  			left_start, left_len, right_start,
  			prototype ? " " : "",
  			prototype ? : "");
  	} else {
  		rc = fprintf(dest, "@@ -%d,%d +%d,%d @@%s%s\n",
  			left_start, left_len, right_start, right_len,
  			prototype ? " " : "",
  			prototype ? : "");
  	}
  	free(prototype);
  	if (rc < 0)
  		return errno;
  	if (outinfo) {
  		ARRAYLIST_ADD(offp, outinfo->line_offsets);
  		if (offp == NULL)
  			return ENOMEM;
  		outoff += rc;
  		*offp = outoff;
  
  	}
  
  	/* Got the absolute line numbers where to start printing, and the index
  	 * of the interesting (non-context) chunk.
  	 * To print context lines above the interesting chunk, nipping on the
  	 * previous chunk index may be necessary.
  	 * It is guaranteed to be only context lines where left == right, so it
  	 * suffices to look on the left. */
  	const struct diff_chunk *first_chunk;
  	int chunk_start_line;
  	first_chunk = &result->chunks.head[cc->chunk.start];
  	chunk_start_line = diff_atom_root_idx(result->left,
  					      first_chunk->left_start);
  	if (cc->left.start < chunk_start_line) {
  		rc = diff_output_lines(outinfo, dest, " ",
  				  &result->left->atoms.head[cc->left.start],
  				  chunk_start_line - cc->left.start);
  		if (rc)
  			return rc;
  	}
  
  	/* Now write out all the joined chunks and contexts between them */
  	int c_idx;
  	for (c_idx = cc->chunk.start; c_idx < cc->chunk.end; c_idx++) {
  		const struct diff_chunk *c = &result->chunks.head[c_idx];
  
  		if (c->left_count && c->right_count)
  			rc = diff_output_lines(outinfo, dest,
  					  c->solved ? " " : "?",
  					  c->left_start, c->left_count);
  		else if (c->left_count && !c->right_count)
  			rc = diff_output_lines(outinfo, dest,
  					  c->solved ? "-" : "?",
  					  c->left_start, c->left_count);
  		else if (c->right_count && !c->left_count)
  			rc = diff_output_lines(outinfo, dest,
  					  c->solved ? "+" : "?",
  					  c->right_start, c->right_count);
  		if (rc)
  			return rc;
  
  		if (cc->chunk.end == result->chunks.len) {
  			rc = diff_output_trailing_newline_msg(outinfo, dest, c);
  			if (rc != DIFF_RC_OK)
  				return rc;
  		}
  	}
  
  	/* Trailing context? */
  	const struct diff_chunk *last_chunk;
  	int chunk_end_line;
  	last_chunk = &result->chunks.head[cc->chunk.end - 1];
  	chunk_end_line = diff_atom_root_idx(result->left,
  					    last_chunk->left_start
  					    + last_chunk->left_count);
  	if (cc->left.end > chunk_end_line) {
  		rc = diff_output_lines(outinfo, dest, " ",
  				  &result->left->atoms.head[chunk_end_line],
  				  cc->left.end - chunk_end_line);
  		if (rc)
  			return rc;
  	}
  
  	return DIFF_RC_OK;
  }
  
  int
  diff_output_unidiff_chunk(struct diff_output_info **output_info, FILE *dest,
  			  struct diff_output_unidiff_state *state,
  			  const struct diff_input_info *info,
  			  const struct diff_result *result,
  			  const struct diff_chunk_context *cc)
  {
  	struct diff_output_info *outinfo = NULL;
  	int flags = (result->left->root->diff_flags |
  	    result->right->root->diff_flags);
  	bool show_function_prototypes = (flags & DIFF_FLAG_SHOW_PROTOTYPES);
  
  	if (output_info) {
  		*output_info = diff_output_info_alloc();
  		if (*output_info == NULL)
  			return ENOMEM;
  		outinfo = *output_info;
  	}
  
  	return output_unidiff_chunk(outinfo, dest, state, info,
  	    result, false, show_function_prototypes, cc);
  }
  
  int
  diff_output_unidiff(struct diff_output_info **output_info,
  		    FILE *dest, const struct diff_input_info *info,
  		    const struct diff_result *result,
  		    unsigned int context_lines)
  {
  	struct diff_output_unidiff_state *state;
  	struct diff_chunk_context cc = {};
  	struct diff_output_info *outinfo = NULL;
  	int flags = (result->left->root->diff_flags |
  	    result->right->root->diff_flags);
  	bool show_function_prototypes = (flags & DIFF_FLAG_SHOW_PROTOTYPES);
  	int i;
  
  	if (!result)
  		return EINVAL;
  	if (result->rc != DIFF_RC_OK)
  		return result->rc;
  
  	if (output_info) {
  		*output_info = diff_output_info_alloc();
  		if (*output_info == NULL)
  			return ENOMEM;
  		outinfo = *output_info;
  	}
  
  	state = diff_output_unidiff_state_alloc();
  	if (state == NULL) {
  		if (output_info) {
  			diff_output_info_free(*output_info);
  			*output_info = NULL;
  		}
  		return ENOMEM;
  	}
  
  #if DEBUG
  	unsigned int check_left_pos, check_right_pos;
  	check_left_pos = 0;
  	check_right_pos = 0;
  	for (i = 0; i < result->chunks.len; i++) {
  		struct diff_chunk *c = &result->chunks.head[i];
  		enum diff_chunk_type t = diff_chunk_type(c);
  
  		debug("[%d] %s lines L%d R%d @L %d @R %d\n",
  		      i, (t == CHUNK_MINUS ? "minus" :
  			  (t == CHUNK_PLUS ? "plus" :
  			   (t == CHUNK_SAME ? "same" : "?"))),
  		      c->left_count,
  		      c->right_count,
  		      c->left_start ? diff_atom_root_idx(result->left, c->left_start) : -1,
  		      c->right_start ? diff_atom_root_idx(result->right, c->right_start) : -1);
  		assert(check_left_pos == diff_atom_root_idx(result->left, c->left_start));
  		assert(check_right_pos == diff_atom_root_idx(result->right, c->right_start));
  		check_left_pos += c->left_count;
  		check_right_pos += c->right_count;
  
  	}
  	assert(check_left_pos == result->left->atoms.len);
  	assert(check_right_pos == result->right->atoms.len);
  #endif
  
  	for (i = 0; i < result->chunks.len; i++) {
  		struct diff_chunk *c = &result->chunks.head[i];
  		enum diff_chunk_type t = diff_chunk_type(c);
  		struct diff_chunk_context next;
  
  		if (t != CHUNK_MINUS && t != CHUNK_PLUS)
  			continue;
  
  		if (diff_chunk_context_empty(&cc)) {
  			/* These are the first lines being printed.
  			 * Note down the start point, any number of subsequent
  			 * chunks may be joined up to this unidiff chunk by
  			 * context lines or by being directly adjacent. */
  			diff_chunk_context_get(&cc, result, i, context_lines);
  			debug("new chunk to be printed:"
  			      " chunk %d-%d left %d-%d right %d-%d\n",
  			      cc.chunk.start, cc.chunk.end,
  			      cc.left.start, cc.left.end,
  			      cc.right.start, cc.right.end);
  			continue;
  		}
  
  		/* There already is a previous chunk noted down for being
  		 * printed. Does it join up with this one? */
  		diff_chunk_context_get(&next, result, i, context_lines);
  		debug("new chunk to be printed:"
  		      " chunk %d-%d left %d-%d right %d-%d\n",
  		      next.chunk.start, next.chunk.end,
  		      next.left.start, next.left.end,
  		      next.right.start, next.right.end);
  
  		if (diff_chunk_contexts_touch(&cc, &next)) {
  			/* This next context touches or overlaps the previous
  			 * one, join. */
  			diff_chunk_contexts_merge(&cc, &next);
  			debug("new chunk to be printed touches previous chunk,"
  			      " now: left %d-%d right %d-%d\n",
  			      cc.left.start, cc.left.end,
  			      cc.right.start, cc.right.end);
  			continue;
  		}
  
  		/* No touching, so the previous context is complete with a gap
  		 * between it and this next one. Print the previous one and
  		 * start fresh here. */
  		debug("new chunk to be printed does not touch previous chunk;"
  		      " print left %d-%d right %d-%d\n",
  		      cc.left.start, cc.left.end, cc.right.start, cc.right.end);
  		output_unidiff_chunk(outinfo, dest, state, info, result,
  		    true, show_function_prototypes, &cc);
  		cc = next;
  		debug("new unprinted chunk is left %d-%d right %d-%d\n",
  		      cc.left.start, cc.left.end, cc.right.start, cc.right.end);
  	}
  
  	if (!diff_chunk_context_empty(&cc))
  		output_unidiff_chunk(outinfo, dest, state, info, result,
  		    true, show_function_prototypes, &cc);
  	diff_output_unidiff_state_free(state);
  	return DIFF_RC_OK;
  }
  

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