func_strings: Add STRBETWEEN function

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

diff --git a/doc/CHANGES-staging/func_strings.txt b/doc/CHANGES-staging/func_strings.txt
new file mode 100644 (file)
index 0000000..d154464
--- /dev/null
+++ b/doc/CHANGES-staging/func_strings.txt
@@ -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.

diff --git a/funcs/func_strings.c b/funcs/func_strings.c
index 7afc40e384670e501437409984f6177f7e86ae75..c70c9bd2f535afa2d17b9175bbde49b65174d914 100644 (file)
--- a/funcs/func_strings.c
+++ b/funcs/func_strings.c
@@ -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
@@ -22,6 +23,7 @@
  *
  * \author Tilghman Lesher
  * \author Anothony Minessale II
+ * \author Naveen Albert
  * \ingroup functions
  */
 
@@ -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.
@@ -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)
 {
@@ -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)
@@ -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);
@@ -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);