164 lines
3.9 KiB
C
164 lines
3.9 KiB
C
// Copyright (C) 2004-2022 Artifex Software, Inc.
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//
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// This file is part of MuPDF.
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//
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// MuPDF is free software: you can redistribute it and/or modify it under the
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// terms of the GNU Affero General Public License as published by the Free
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// Software Foundation, either version 3 of the License, or (at your option)
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// any later version.
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//
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// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
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// details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
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//
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// Alternative licensing terms are available from the licensor.
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// For commercial licensing, see <https://www.artifex.com/> or contact
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// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
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// CA 94129, USA, for further information.
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/* This file has preprocessor magic in it to instantiate both
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* protoypes and implementations for heap sorting structures
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* of various different types. Effectively, it's templating for
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* C.
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*
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* If you are including this file directly without intending to
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* be instantiating a new set of heap sort functions, you are
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* doing the wrong thing.
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*/
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#ifndef MUPDF_FITZ_HEAP_I_KNOW_WHAT_IM_DOING
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#error Do not include heap-imp.h unless you know what youre doing
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#endif
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#define HEAP_XCAT(A,B) A##B
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#define HEAP_CAT(A,B) HEAP_XCAT(A,B)
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#ifndef MUPDF_FITZ_HEAP_IMPLEMENT
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typedef struct
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{
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int max;
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int len;
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HEAP_CONTAINER_TYPE *heap;
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} HEAP_TYPE_NAME;
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#endif
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void HEAP_CAT(HEAP_TYPE_NAME,_insert)(fz_context *ctx, HEAP_TYPE_NAME *heap, HEAP_CONTAINER_TYPE v
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#ifndef HEAP_CMP
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, int (*HEAP_CMP)(HEAP_CONTAINER_TYPE *a, HEAP_CONTAINER_TYPE *b)
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#endif
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)
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#ifndef MUPDF_FITZ_HEAP_IMPLEMENT
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;
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#else
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{
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int i;
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HEAP_CONTAINER_TYPE *h;
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if (heap->max == heap->len)
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{
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int m = heap->max * 2;
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if (m == 0)
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m = 32;
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heap->heap = (HEAP_CONTAINER_TYPE *)fz_realloc(ctx, heap->heap, sizeof(*heap->heap) * m);
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heap->max = m;
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}
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h = heap->heap;
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/* Insert it into the heap. Consider inserting at position i, and
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* then 'heapify' back. We can delay the actual insertion to the
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* end of the process. */
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i = heap->len++;
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while (i != 0)
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{
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int parent_idx = (i-1)/2;
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HEAP_CONTAINER_TYPE *parent_val = &h[parent_idx];
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if (HEAP_CMP(parent_val, &v) > 0)
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break;
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h[i] = h[parent_idx];
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i = parent_idx;
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}
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h[i] = v;
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}
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#endif
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void HEAP_CAT(HEAP_TYPE_NAME,_sort)(fz_context *ctx, HEAP_TYPE_NAME *heap
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#ifndef HEAP_CMP
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, int (*HEAP_CMP)(HEAP_CONTAINER_TYPE *a, HEAP_CONTAINER_TYPE *b)
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#endif
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)
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#ifndef MUPDF_FITZ_HEAP_IMPLEMENT
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;
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#else
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{
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int j;
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HEAP_CONTAINER_TYPE *h = heap->heap;
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/* elements j to len are always sorted. 0 to j are always a valid heap. Gradually move j to 0. */
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for (j = heap->len-1; j > 0; j--)
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{
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int k;
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HEAP_CONTAINER_TYPE val;
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/* Swap max element with j. Invariant valid for next value to j. */
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val = h[j];
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h[j] = h[0];
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/* Now reform the heap. 0 to k is a valid heap. */
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k = 0;
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while (1)
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{
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int kid = k*2+1;
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if (kid >= j)
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break;
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if (kid+1 < j && (HEAP_CMP(&h[kid+1], &h[kid])) > 0)
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kid++;
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if ((HEAP_CMP(&val, &h[kid])) > 0)
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break;
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h[k] = h[kid];
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k = kid;
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}
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h[k] = val;
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}
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}
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#endif
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void HEAP_CAT(HEAP_TYPE_NAME,_uniq)(fz_context *ctx, HEAP_TYPE_NAME *heap
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#ifndef HEAP_CMP
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, int (*HEAP_CMP)(HEAP_CONTAINER_TYPE *a, HEAP_CONTAINER_TYPE *b)
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#endif
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)
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#ifndef MUPDF_FITZ_HEAP_IMPLEMENT
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;
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#else
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{
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int n = heap->len;
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int i, j = 0;
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HEAP_CONTAINER_TYPE *h = heap->heap;
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if (n == 0)
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return;
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j = 0;
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for (i = 1; i < n; i++)
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{
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if (HEAP_CMP(&h[j], &h[i]) == 0)
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continue;
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j++;
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if (i != j)
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h[j] = h[i];
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}
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heap->len = j+1;
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}
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#endif
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#undef HEAP_CONTAINER_TYPE
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#undef HEAP_TYPE_NAME
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#undef HEAP_CMP
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#undef HEAP_XCAT
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#undef HEAP_CAT
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