[FFmpeg-devel] [PATCH] lavu: add stringinterp interface
Stefano Sabatini
stefasab at gmail.com
Sat Dec 7 10:43:17 CET 2013
From: Clément Bœsch <u at pkh.me>
With very minor changes by Stefano Sabatini.
Based on thread:
From: Clément Bœsch <ubitux at gmail.com>
Subject: [FFmpeg-devel] [PATCH] WIP/lavu: add string interpolation helper.
Date: 2012-02-01 11:01:02 GMT
Signed-off-by: Stefano Sabatini <stefasab at gmail.com>
TODO: bump major, add APIchanges entry, mark as experimental?
---
libavutil/Makefile | 2 +
libavutil/stringinterp.c | 207 +++++++++++++++++++++++++++++++++++++++++++++++
libavutil/stringinterp.h | 66 +++++++++++++++
3 files changed, 275 insertions(+)
create mode 100644 libavutil/stringinterp.c
create mode 100644 libavutil/stringinterp.h
diff --git a/libavutil/Makefile b/libavutil/Makefile
index 5e0c4ae..c30caae 100644
--- a/libavutil/Makefile
+++ b/libavutil/Makefile
@@ -110,6 +110,7 @@ OBJS = adler32.o \
samplefmt.o \
sha.o \
sha512.o \
+ stringinterp.o \
time.o \
timecode.o \
tree.o \
@@ -158,6 +159,7 @@ TESTPROGS = adler32 \
random_seed \
rational \
ripemd \
+ stringinterp \
sha \
sha512 \
tree \
diff --git a/libavutil/stringinterp.c b/libavutil/stringinterp.c
new file mode 100644
index 0000000..d1d4fc1
--- /dev/null
+++ b/libavutil/stringinterp.c
@@ -0,0 +1,207 @@
+/*
+ * Copyright (c) 2012 Clément Bœsch
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * string interpolation
+ */
+
+#include "avutil.h"
+#include "avstring.h"
+#include "stringinterp.h"
+
+struct node {
+ const char *key;
+ const char *value;
+ struct node *next;
+};
+
+typedef struct AVStringInterp {
+ struct node *hashtable[512];
+ char *buf;
+ size_t buf_size;
+} AVStringInterp;
+
+AVStringInterp *av_stringinterp_alloc(void)
+{
+ AVStringInterp *ctx = av_mallocz(sizeof(*ctx));
+
+ if (!ctx)
+ return NULL;
+ ctx->buf = av_malloc(128);
+ if (!ctx->buf) {
+ av_free(ctx);
+ return NULL;
+ }
+ ctx->buf_size = 128;
+ return ctx;
+}
+
+void av_stringinterp_free(AVStringInterp **ctx)
+{
+ int i;
+ AVStringInterp *s = *ctx;
+ for (i = 0; i < FF_ARRAY_ELEMS(s->hashtable); i++) {
+ struct node *tmp, *node = s->hashtable[i];
+ while (node) {
+ tmp = node;
+ node = node->next;
+ av_freep(&tmp);
+ }
+ }
+ av_freep(&s->buf);
+ av_freep(ctx);
+}
+
+static uint32_t get_hash(const char *key, size_t len, int tbl_len)
+{
+ size_t i;
+ uint32_t hash = 0;
+ for (i = 0; i < len; i++)
+ hash = (hash<<5) ^ (hash>>27) ^ key[i];
+ return hash % tbl_len;
+}
+
+static struct node *create_node(const char *key, const char *value)
+{
+ struct node *node = av_mallocz(sizeof(*node));
+ if (!node)
+ return NULL;
+ node->key = key;
+ node->value = value;
+ return node;
+}
+
+int av_stringinterp_map(AVStringInterp *ctx, const char *key, const char *value)
+{
+ uint32_t id = get_hash(key, strlen(key), FF_ARRAY_ELEMS(ctx->hashtable));
+ struct node *node = ctx->hashtable[id];
+ struct node *insert_after = NULL;
+
+ while (node) {
+ if (!strcmp(key, node->key)) {
+ node->value = value;
+ return 0;
+ }
+ insert_after = node;
+ node = node->next;
+ }
+ node = create_node(key, value);
+ if (!node)
+ return AVERROR(ENOMEM);
+ if (insert_after)
+ insert_after->next = node;
+ else
+ ctx->hashtable[id] = node;
+ return 0;
+}
+
+static const char *get_value(AVStringInterp *ctx, const char *key)
+{
+ int id;
+ size_t keylen;
+ const char *p = strchr(key, ')');
+ struct node *node;
+
+ if (!p)
+ return NULL;
+ keylen = p - key;
+ id = get_hash(key, keylen, FF_ARRAY_ELEMS(ctx->hashtable));
+ for (node = ctx->hashtable[id]; node; node = node->next)
+ if (!strncmp(key, node->key, keylen))
+ return node->value;
+ return NULL;
+}
+
+#define APPEND_STRING(str, slen) do { \
+ size_t new_size = pos + slen + 1; \
+ if (new_size > ctx->buf_size) { \
+ char *ptr = av_realloc(ctx->buf, new_size); \
+ if (!ptr) \
+ return NULL; \
+ ctx->buf = ptr; \
+ ctx->buf_size = new_size; \
+ } \
+ av_strlcpy(ctx->buf + pos, str, slen + 1); \
+ pos += slen; \
+} while (0)
+
+char *av_stringinterp_interpolate(AVStringInterp *ctx, const char *s)
+{
+ const char *p;
+ size_t pos = 0;
+
+ while (*s) {
+ if (s[0] == '%' && s[1] == '(') {
+ const char *value = get_value(ctx, s + 2);
+ if (value) {
+ APPEND_STRING(value, strlen(value));
+ s = strchr(s, ')') + 1;
+ continue;
+ }
+ }
+ p = strchr(s + 1, '%');
+ if (!p) {
+ APPEND_STRING(s, strlen(s));
+ break;
+ }
+ APPEND_STRING(s, p - s);
+ s = p;
+ }
+ return ctx->buf;
+}
+
+#ifdef TEST
+
+static void dump_table(AVStringInterp *ctx)
+{
+ int i;
+ printf("Hashtable dump:\n");
+ for (i = 0; i < FF_ARRAY_ELEMS(ctx->hashtable); i++) {
+ struct node *node = ctx->hashtable[i];
+ if (!node)
+ continue;
+ printf(" [%02d/%02ld]:", i, FF_ARRAY_ELEMS(ctx->hashtable));
+ while (node) {
+ printf(" \"%s\"=>\"%s\"", node->key, node->value);
+ node = node->next;
+ }
+ printf("\n");
+ }
+}
+
+int main(int ac, char **av)
+{
+ AVStringInterp *si = av_stringinterp_alloc();
+
+ av_stringinterp_map(si, "ts1", "0.4123");
+ av_stringinterp_map(si, "ts2", "54.153");
+ av_stringinterp_map(si, "filename", "FooBar");
+ av_stringinterp_map(si, "ext", ".mpg");
+ av_stringinterp_map(si, "ext", ".mp4");
+
+ dump_table(si);
+
+ printf("%s\n",
+ av_stringinterp_interpolate(si, "%(filename)_%(ts1)-%(ts2)_%(nokey)%(ext)"));
+ av_stringinterp_free(&si);
+ return 0;
+}
+#endif
diff --git a/libavutil/stringinterp.h b/libavutil/stringinterp.h
new file mode 100644
index 0000000..a2331ad
--- /dev/null
+++ b/libavutil/stringinterp.h
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2012 Clément Bœsch
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * string interpolation header
+ */
+
+#ifndef AVUTIL_STRINGINTERP_H
+#define AVUTIL_STRINGINTERP_H
+
+typedef struct AVStringInterp AVStringInterp;
+
+/**
+ * Allocate a new string interpolation context.
+ */
+AVStringInterp *av_stringinterp_alloc(void);
+
+/**
+ * Free a AVStringInterp context previously created with
+ * av_stringinterp_alloc().
+ */
+void av_stringinterp_free(AVStringInterp **ctx);
+
+/**
+ * Map a key string with a value string.
+ *
+ * If the key already exists, the value is replaced.
+ * @return 0 in case of success, a negative AVERROR code otherwise
+ * @note key and value are not duplicated, you must keep a reference
+ * to them.
+ */
+int av_stringinterp_map(AVStringInterp *ctx, const char *key, const char *value);
+
+/**
+ * Do the string interpolation.
+ *
+ * The value to interpolate must have the form "%(key)", where key is
+ * the name to be changed with the value previously stored in the
+ * AVStringInterp structure. In case the key is not recognized, it is
+ * ignored.
+ *
+ * @return a pointer to the printable string, or NULL in case of failure
+ * @note The returned buffer is kept in the AVStringInterp context, you must
+ * not free it.
+ */
+char *av_stringinterp_interpolate(AVStringInterp *ctx, const char *s);
+
+#endif/* AVUTIL_STRINGINTERP_H */
--
1.8.1.2
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