cli: Support arrays in parameters

This patch adds support for arrays in the parameters one can pass to
components on the Babeltrace command line.  For example:

  --params="value=[1,2,\"Hello\"]"

When we are starting to parse a value and the token is a '[', we start
parsing it as an array.  We accept comma-separated values until we reach
the matching ']'. The code should be pretty self-explanatory/commented.

Signed-off-by: Simon Marchi <simon.marchi@efficios.com>

diff --git a/cli/babeltrace-cfg-cli-args.c b/cli/babeltrace-cfg-cli-args.c
index b71b70f532233c360d8bd715cdf907682d486e86..927a85d931482e8d285ac692f45d004ce97a7339 100644 (file)
--- a/cli/babeltrace-cfg-cli-args.c
+++ b/cli/babeltrace-cfg-cli-args.c
@@ -220,6 +220,77 @@ bt_value *ini_parse_neg_number(struct ini_parsing_state *state)
        return value;
 }
 
+static bt_value *ini_parse_value(struct ini_parsing_state *state);
+
+/*
+ * Parse the current and following tokens as an array.  Arrays are formatted as
+ * an opening `[`, a list of comma-separated values and a closing `]`.  For
+ * convenience we support an optional trailing comma, after the last value.
+ *
+ * The current token of the parser must be the opening square bracket of the
+ * array.
+ */
+static
+bt_value *ini_parse_array(struct ini_parsing_state *state)
+{
+       /* The [ character must have already been ingested. */
+       BT_ASSERT(g_scanner_cur_token(state->scanner) == G_TOKEN_CHAR);
+       BT_ASSERT(g_scanner_cur_value(state->scanner).v_char == '[');
+
+       bt_value *array_value;
+       GTokenType token_type;
+
+       array_value = bt_value_array_create ();
+       token_type = g_scanner_get_next_token(state->scanner);
+
+       /* While the current token is not a ]... */
+       while (!(token_type == G_TOKEN_CHAR && g_scanner_cur_value(state->scanner).v_char == ']')) {
+               /* Parse the item... */
+               bt_value *item_value;
+               bt_value_status status;
+
+               item_value = ini_parse_value(state);
+               if (!item_value) {
+                       goto error;
+               }
+
+               /* ... and add it to the result array. */
+               status = bt_value_array_append_element(array_value, item_value);
+               BT_VALUE_PUT_REF_AND_RESET(item_value);
+
+               if (status != BT_VALUE_STATUS_OK) {
+                       goto error;
+               }
+
+               /*
+                * Ingest the token following the value, it should be either a
+                * comma or closing square brace.
+                */
+               token_type = g_scanner_get_next_token(state->scanner);
+
+               if (token_type == G_TOKEN_CHAR && g_scanner_cur_value(state->scanner).v_char == ',') {
+                       /*
+                        * Ingest the token following the comma.  If it happens
+                        * to be a closing square bracket, we'll exit the loop
+                        * and we are done (we allow trailing commas).
+                        * Otherwise, we are ready for the next ini_parse_value call.
+                        */
+                       token_type = g_scanner_get_next_token(state->scanner);
+               } else if (token_type != G_TOKEN_CHAR || g_scanner_cur_value(state->scanner).v_char != ']') {
+                       ini_append_error_expecting(state, state->scanner, ", or ]");
+                       goto error;
+               }
+       }
+
+       goto end;
+
+error:
+       BT_VALUE_PUT_REF_AND_RESET(array_value);
+
+end:
+       return array_value;
+}
+
 /*
  * Parse the current token (and the following ones if needed) as a value, return
  * it as a bt_value.
@@ -235,6 +306,9 @@ bt_value *ini_parse_value(struct ini_parsing_state *state)
                if (state->scanner->value.v_char == '-') {
                        /* Negative number */
                        value = ini_parse_neg_number(state);
+               } else if (state->scanner->value.v_char == '[') {
+                       /* Array */
+                       value = ini_parse_array(state);
                } else {
                        ini_append_error_expecting(state, state->scanner, "value");
                }
@@ -1769,6 +1843,8 @@ void print_expected_params_format(FILE *fp)
        fprintf(fp, "* Unquoted string with no special characters, and not matching any of\n");
        fprintf(fp, "  the null and boolean value symbols above.\n");
        fprintf(fp, "* Double-quoted string (accepts escape characters).\n");
+       fprintf(fp, "* Array, formatted as an opening `[`, a list of comma-separated values\n");
+       fprintf(fp, "  (as described by the current list) and a closing `]`.\n");
        fprintf(fp, "\n");
        fprintf(fp, "You can put whitespaces allowed around individual `=` and `,` symbols.\n");
        fprintf(fp, "\n");
@@ -1776,7 +1852,8 @@ void print_expected_params_format(FILE *fp)
        fprintf(fp, "\n");
        fprintf(fp, "    many=null, fresh=yes, condition=false, squirrel=-782329,\n");
        fprintf(fp, "    observe=3.14, simple=beef, needs-quotes=\"some string\",\n");
-       fprintf(fp, "    escape.chars-are:allowed=\"this is a \\\" double quote\"\n");
+       fprintf(fp, "    escape.chars-are:allowed=\"this is a \\\" double quote\",\n");
+       fprintf(fp, "    things=[1, \"2\", 3]\n");
        fprintf(fp, "\n");
        fprintf(fp, "IMPORTANT: Make sure to single-quote the whole argument when you run\n");
        fprintf(fp, "babeltrace from a shell.\n");

diff --git a/doc/man/common-cmd-params-format.txt b/doc/man/common-cmd-params-format.txt
index c3ee8d4fe7e0846bedcbc1384752655035eb1985..efceab479f4c4353b6fa13ecec39101ae7a210d5 100644 (file)
--- a/doc/man/common-cmd-params-format.txt
+++ b/doc/man/common-cmd-params-format.txt
@@ -31,6 +31,9 @@ list of `NAME=VALUE` assignments:
 
 * Double-quoted string (accepts escape characters).
 
+* Array, formatted as an opening `[`, a list of comma-separated values
+  (as described by the current list) and a closing `]`.
+
 You may put whitespaces around the individual `=` (assignment) and `,`
 (separator) characters.
 --
@@ -41,7 +44,8 @@ Example:
 babeltrace ... --params='many=null, fresh=yes, condition=false,
                          squirrel=-782329, observe=3.14,
                          simple=beef, needs-quotes="some string",
-                         escape.chars-are:allowed="a \" quote"'
+                         escape.chars-are:allowed="a \" quote",
+                         things=[1, "2", 3]'
 ----
 
 IMPORTANT: Like in the example above, make sure to single-quote the