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func_strings: Add STRBETWEEN function
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Adds the STRBETWEEN function, which can be used to insert a
substring between each character in a string. For instance,
this can be used to insert pauses between DTMF tones in a
string of digits.

ASTERISK-29627

Change-Id: Ice23009d4a8e9bb9718d2b2301d405567087d258
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@InterLinked1
InterLinked1 authored and Friendly Automation committed Sep 10, 2021
1 parent c4037d4 commit b8fc77a
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7 changes: 7 additions & 0 deletions doc/CHANGES-staging/func_strings.txt
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@@ -0,0 +1,7 @@
Subject: func_strings

A new STRBETWEEN function is now included which
allows a substring to be inserted between characters
in a string. This is particularly useful for transforming
dial strings, such as adding pauses between digits
for a string of digits that are sent to another channel.
144 changes: 144 additions & 0 deletions funcs/func_strings.c
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Expand Up @@ -4,6 +4,7 @@
* Copyright (C) 2005-2006, Digium, Inc.
* Portions Copyright (C) 2005, Tilghman Lesher. All rights reserved.
* Portions Copyright (C) 2005, Anthony Minessale II
* Portions Copyright (C) 2021, Naveen Albert
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
Expand All @@ -22,6 +23,7 @@
*
* \author Tilghman Lesher
* \author Anothony Minessale II
* \author Naveen Albert
* \ingroup functions
*/

Expand Down Expand Up @@ -152,6 +154,24 @@ AST_THREADSTORAGE(tmp_buf);
<note><para>The replacement only occurs in the output. The original variable is not altered.</para></note>
</description>
</function>
<function name="STRBETWEEN" language="en_US">
<synopsis>
Inserts a substring between each character in a string.
</synopsis>
<syntax>
<parameter name="varname" required="true" />
<parameter name="insert-string" required="true" />
</syntax>
<description>
<para>Inserts a substring <replaceable>find-string</replaceable> between each character in
<replaceable>varname</replaceable>.</para>
<note><para>The replacement only occurs in the output. The original variable is not altered.</para></note>
<example title="Add half-second pause between dialed digits">
same => n,Set(digits=5551212)
same => n,SendDTMF(${STRBETWEEN(digits,w)) ; this will send 5w5w5w1w2w1w2
</example>
</description>
</function>
<function name="PASSTHRU" language="en_US">
<synopsis>
Pass the given argument back as a value.
Expand Down Expand Up @@ -945,6 +965,53 @@ static struct ast_custom_function strreplace_function = {
.read2 = strreplace,
};

static int strbetween(struct ast_channel *chan, const char *cmd, char *data, struct ast_str **buf, ssize_t len)
{
int c, origsize;
char *varsubstr, *origstr;
struct ast_str *str = ast_str_thread_get(&result_buf, 16); /* Holds the data obtained from varname */

AST_DECLARE_APP_ARGS(args,
AST_APP_ARG(varname);
AST_APP_ARG(insert_string);
AST_APP_ARG(other); /* Any remining unused arguments */
);

ast_str_reset(*buf);

if (!str) {
ast_log(LOG_ERROR, "Couldn't obtain string\n");
return -1;
}

AST_STANDARD_APP_ARGS(args, data);

if (args.argc != 2 || ast_strlen_zero(args.varname)) {
ast_log(LOG_ERROR, "Usage: %s(<varname>,<insert-string>)\n", cmd);
return -1;
}

varsubstr = ast_alloca(strlen(args.varname) + 4);
sprintf(varsubstr, "${%s}", args.varname);
ast_str_substitute_variables(&str, 0, chan, varsubstr);
origstr = ast_str_buffer(str);
origsize = strlen(origstr);
for (c = 0; c < origsize; c++) {
ast_str_append(buf, len, "%c", origstr[c]);
/* no insert after the last character */
if (c < (origsize - 1)) {
ast_str_append(buf, len, "%s", args.insert_string);
}
}

return 0;
}

static struct ast_custom_function strbetween_function = {
.name = "STRBETWEEN",
.read2 = strbetween,
};

static int regex(struct ast_channel *chan, const char *cmd, char *parse, char *buf,
size_t len)
{
Expand Down Expand Up @@ -1953,6 +2020,79 @@ AST_TEST_DEFINE(test_STRREPLACE)

return res;
}

AST_TEST_DEFINE(test_STRBETWEEN)
{
int i, res = AST_TEST_PASS;
struct ast_channel *chan; /* dummy channel */
struct ast_str *str; /* fancy string for holding comparing value */

const char *test_strings[][5] = {
{"0", "w", "0"},
{"30", "w", "3w0"},
{"212", "w", "2w1w2"},
{"212", "55", "2551552"},
{"212", " ", "2 1 2"},
{"", "w", ""},
{"555", "", "555"},
{"abcdefg", "_", "a_b_c_d_e_f_g"},
{"A", "A", "A"},
{"AA", "B", "ABA"},
{"AAA", "B", "ABABA"},
};

switch (cmd) {
case TEST_INIT:
info->name = "func_STRBETWEEN";
info->category = "/funcs/func_strings/";
info->summary = "Test STRBETWEEN function";
info->description = "Verify STRBETWEEN behavior";
return AST_TEST_NOT_RUN;
case TEST_EXECUTE:
break;
}

if (!(chan = ast_dummy_channel_alloc())) {
ast_test_status_update(test, "Unable to allocate dummy channel\n");
return AST_TEST_FAIL;
}

if (!(str = ast_str_create(64))) {
ast_test_status_update(test, "Unable to allocate dynamic string buffer\n");
ast_channel_release(chan);
return AST_TEST_FAIL;
}

for (i = 0; i < ARRAY_LEN(test_strings); i++) {
char tmp[512], tmp2[512] = "";

struct ast_var_t *var = ast_var_assign("test_string", test_strings[i][0]);
if (!var) {
ast_test_status_update(test, "Unable to allocate variable\n");
ast_free(str);
ast_channel_release(chan);
return AST_TEST_FAIL;
}

AST_LIST_INSERT_HEAD(ast_channel_varshead(chan), var, entries);

if (test_strings[i][1]) {
snprintf(tmp, sizeof(tmp), "${STRBETWEEN(%s,%s)}", "test_string", test_strings[i][1]);
} else {
snprintf(tmp, sizeof(tmp), "${STRBETWEEN(%s)}", "test_string");
}
ast_str_substitute_variables(&str, 0, chan, tmp);
if (strcmp(test_strings[i][2], ast_str_buffer(str))) {
ast_test_status_update(test, "Format string '%s' substituted to '%s'. Expected '%s'.\n", test_strings[i][0], tmp2, test_strings[i][2]);
res = AST_TEST_FAIL;
}
}

ast_free(str);
ast_channel_release(chan);

return res;
}
#endif

static int unload_module(void)
Expand All @@ -1963,11 +2103,13 @@ static int unload_module(void)
AST_TEST_UNREGISTER(test_REPLACE);
AST_TEST_UNREGISTER(test_FILTER);
AST_TEST_UNREGISTER(test_STRREPLACE);
AST_TEST_UNREGISTER(test_STRBETWEEN);
res |= ast_custom_function_unregister(&fieldqty_function);
res |= ast_custom_function_unregister(&fieldnum_function);
res |= ast_custom_function_unregister(&filter_function);
res |= ast_custom_function_unregister(&replace_function);
res |= ast_custom_function_unregister(&strreplace_function);
res |= ast_custom_function_unregister(&strbetween_function);
res |= ast_custom_function_unregister(&listfilter_function);
res |= ast_custom_function_unregister(&regex_function);
res |= ast_custom_function_unregister(&array_function);
Expand Down Expand Up @@ -2000,11 +2142,13 @@ static int load_module(void)
AST_TEST_REGISTER(test_REPLACE);
AST_TEST_REGISTER(test_FILTER);
AST_TEST_REGISTER(test_STRREPLACE);
AST_TEST_REGISTER(test_STRBETWEEN);
res |= ast_custom_function_register(&fieldqty_function);
res |= ast_custom_function_register(&fieldnum_function);
res |= ast_custom_function_register(&filter_function);
res |= ast_custom_function_register(&replace_function);
res |= ast_custom_function_register(&strreplace_function);
res |= ast_custom_function_register(&strbetween_function);
res |= ast_custom_function_register(&listfilter_function);
res |= ast_custom_function_register(&regex_function);
res |= ast_custom_function_register(&array_function);
Expand Down

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