input/csv: eliminate magic numbers in options declaration

The CSV input module has grown so many options, that counting them by
hand became tedious and error prone. Eliminate the magic numbers in the
associated code paths.

This also has the side effect that the set is easy to re-order just by
adjusting the enum, no other code is affected. Help text and default
values is much easier to verify and adjust with the symbolic references.

[ see 'git diff --word-diff' for the essence of the change ]

Author: gsigh

src/input/csv.c

@@ -965,38 +965,51 @@ static int reset(struct sr_input *in)
 	return SR_OK;
 }
 
+enum option_index {
+	OPT_SINGLE_COL,
+	OPT_NUM_LOGIC,
+	OPT_DELIM,
+	OPT_FORMAT,
+	OPT_COMMENT,
+	OPT_RATE,
+	OPT_FIRST_LOGIC,
+	OPT_HEADER,
+	OPT_START,
+	OPT_MAX,
+};
+
 static struct sr_option options[] = {
-	{ "single-column", "Single column", "Enable single-column mode, using the specified column (>= 1); 0: multi-col. mode", NULL, NULL },
-	{ "numchannels", "Number of logic channels", "The number of (logic) channels (single-col. mode: number of bits beginning at 'first channel', LSB-first)", NULL, NULL },
-	{ "delimiter", "Column delimiter", "The column delimiter (>= 1 characters)", NULL, NULL },
-	{ "format", "Data format (single-col. mode)", "The numeric format of the data (single-col. mode): bin, hex, oct", NULL, NULL },
-	{ "comment", "Comment character(s)", "The comment prefix character(s)", NULL, NULL },
-	{ "samplerate", "Samplerate (Hz)", "The sample rate (used during capture) in Hz", NULL, NULL },
-	{ "first-channel", "First channel", "The column number of the first channel (multi-col. mode); bit position for the first channel (single-col. mode)", NULL, NULL },
-	{ "header", "Interpret first line as header (multi-col. mode)", "Treat the first line as header with channel names (multi-col. mode)", NULL, NULL },
-	{ "startline", "Start line", "The line number at which to start processing samples (>= 1)", NULL, NULL },
-	ALL_ZERO
+	[OPT_SINGLE_COL] = { "single-column", "Single column", "Enable single-column mode, using the specified column (>= 1); 0: multi-col. mode", NULL, NULL },
+	[OPT_NUM_LOGIC] = { "numchannels", "Number of logic channels", "The number of (logic) channels (single-col. mode: number of bits beginning at 'first channel', LSB-first)", NULL, NULL },
+	[OPT_DELIM] = { "delimiter", "Column delimiter", "The column delimiter (>= 1 characters)", NULL, NULL },
+	[OPT_FORMAT] = { "format", "Data format (single-col. mode)", "The numeric format of the data (single-col. mode): bin, hex, oct", NULL, NULL },
+	[OPT_COMMENT] = { "comment", "Comment character(s)", "The comment prefix character(s)", NULL, NULL },
+	[OPT_RATE] = { "samplerate", "Samplerate (Hz)", "The sample rate (used during capture) in Hz", NULL, NULL },
+	[OPT_FIRST_LOGIC] = { "first-channel", "First channel", "The column number of the first channel (multi-col. mode); bit position for the first channel (single-col. mode)", NULL, NULL },
+	[OPT_HEADER] = { "header", "Interpret first line as header (multi-col. mode)", "Treat the first line as header with channel names (multi-col. mode)", NULL, NULL },
+	[OPT_START] = { "startline", "Start line", "The line number at which to start processing samples (>= 1)", NULL, NULL },
+	[OPT_MAX] = ALL_ZERO,
 };
 
 static const struct sr_option *get_options(void)
 {
 	GSList *l;
 
 	if (!options[0].def) {
-		options[0].def = g_variant_ref_sink(g_variant_new_int32(0));
-		options[1].def = g_variant_ref_sink(g_variant_new_int32(0));
-		options[2].def = g_variant_ref_sink(g_variant_new_string(","));
-		options[3].def = g_variant_ref_sink(g_variant_new_string("bin"));
+		options[OPT_SINGLE_COL].def = g_variant_ref_sink(g_variant_new_int32(0));
+		options[OPT_NUM_LOGIC].def = g_variant_ref_sink(g_variant_new_int32(0));
+		options[OPT_DELIM].def = g_variant_ref_sink(g_variant_new_string(","));
+		options[OPT_FORMAT].def = g_variant_ref_sink(g_variant_new_string("bin"));
 		l = NULL;
 		l = g_slist_append(l, g_variant_ref_sink(g_variant_new_string("bin")));
 		l = g_slist_append(l, g_variant_ref_sink(g_variant_new_string("hex")));
 		l = g_slist_append(l, g_variant_ref_sink(g_variant_new_string("oct")));
-		options[3].values = l;
-		options[4].def = g_variant_ref_sink(g_variant_new_string(";"));
-		options[5].def = g_variant_ref_sink(g_variant_new_uint64(0));
-		options[6].def = g_variant_ref_sink(g_variant_new_int32(0));
-		options[7].def = g_variant_ref_sink(g_variant_new_boolean(FALSE));
-		options[8].def = g_variant_ref_sink(g_variant_new_int32(1));
+		options[OPT_FORMAT].values = l;
+		options[OPT_COMMENT].def = g_variant_ref_sink(g_variant_new_string(";"));
+		options[OPT_RATE].def = g_variant_ref_sink(g_variant_new_uint64(0));
+		options[OPT_FIRST_LOGIC].def = g_variant_ref_sink(g_variant_new_int32(0));
+		options[OPT_HEADER].def = g_variant_ref_sink(g_variant_new_boolean(FALSE));
+		options[OPT_START].def = g_variant_ref_sink(g_variant_new_int32(1));
 	}
 
 	return options;