command-line-arguments.[ch]: new argument parsing framework for notmuch.

As we noticed when Jani kindly converted things to getopt_long, much
of the work in argument parsing in notmuch is due to the the key-value
style arguments like --format=(raw|json|text).

The framework here provides positional arguments, simple switches,
and --key=value style arguments that can take a value being an integer,
a string, or one of a set of keywords.

Makefile.local

@@ -295,6 +295,7 @@ clean:
 distclean: clean
 
 notmuch_client_srcs =		\
+	command-line-arguments.c\
 	debugger.c		\
 	gmime-filter-reply.c	\
 	gmime-filter-headers.c	\

command-line-arguments.c

@@ -0,0 +1,155 @@
+#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+#include "error_util.h"
+#include "command-line-arguments.h"
+
+/*
+  Search the array of keywords for a given argument, assigning the
+  output variable to the corresponding value.  Return FALSE if nothing
+  matches.
+*/
+
+static notmuch_bool_t
+_process_keyword_arg (const notmuch_opt_desc_t *arg_desc, const char *arg_str) {
+
+    notmuch_keyword_t *keywords = arg_desc->keywords;
+
+    while (keywords->name) {
+	if (strcmp (arg_str, keywords->name) == 0) {
+	    if (arg_desc->output_var) {
+		*((int *)arg_desc->output_var) = keywords->value;
+	    }
+	    return TRUE;
+	}
+	keywords++;
+    }
+    fprintf (stderr, "unknown keyword: %s\n", arg_str);
+    return FALSE;
+}
+
+/*
+   Search for the {pos_arg_index}th position argument, return FALSE if
+   that does not exist.
+*/
+
+notmuch_bool_t
+parse_position_arg (const char *arg_str, int pos_arg_index,
+		    const notmuch_opt_desc_t *arg_desc) {
+
+    int pos_arg_counter = 0;
+    while (arg_desc->opt_type != NOTMUCH_OPT_END){
+	if (arg_desc->opt_type == NOTMUCH_OPT_POSITION) {
+	    if (pos_arg_counter == pos_arg_index) {
+		if (arg_desc->output_var) {
+		    *((const char **)arg_desc->output_var) = arg_str;
+		}
+		return TRUE;
+	    }
+	    pos_arg_counter++;
+	}
+	arg_desc++;
+    }
+    return FALSE;
+}
+
+/*
+ * Search for a non-positional (i.e. starting with --) argument matching arg,
+ * parse a possible value, and assign to *output_var
+ */
+
+notmuch_bool_t
+parse_option (const char *arg,
+	      const notmuch_opt_desc_t *options) {
+
+    assert(arg);
+    assert(options);
+
+    arg += 2;
+
+    const notmuch_opt_desc_t *try = options;
+    while (try->opt_type != NOTMUCH_OPT_END) {
+	if (try->name && strncmp (arg, try->name, strlen (try->name)) == 0) {
+	    char next = arg[strlen (try->name)];
+	    const char *value= arg+strlen(try->name)+1;
+
+	    char *endptr;
+
+	    /* Everything but boolean arguments (switches) needs a
+	     * delimiter, and a non-zero length value
+	     */
+
+	    if (try->opt_type != NOTMUCH_OPT_BOOLEAN) {
+		if (next != '=' && next != ':') return FALSE;
+		if (value[0] == 0) return FALSE;
+	    } else {
+		if (next != 0) return FALSE;
+	    }
+
+	    if (try->output_var == NULL)
+		INTERNAL_ERROR ("output pointer NULL for option %s", try->name);
+
+	    switch (try->opt_type) {
+	    case NOTMUCH_OPT_KEYWORD:
+		return _process_keyword_arg (try, value);
+		break;
+	    case NOTMUCH_OPT_BOOLEAN:
+		*((notmuch_bool_t *)try->output_var) = TRUE;
+		return TRUE;
+		break;
+	    case NOTMUCH_OPT_INT:
+		*((int *)try->output_var) = strtol (value, &endptr, 10);
+		return (*endptr == 0);
+		break;
+	    case NOTMUCH_OPT_STRING:
+		*((const char **)try->output_var) = value;
+		return TRUE;
+		break;
+	    case NOTMUCH_OPT_POSITION:
+	    case NOTMUCH_OPT_END:
+	    default:
+		INTERNAL_ERROR ("unknown or unhandled option type %d", try->opt_type);
+		/*UNREACHED*/
+	    }
+	}
+	try++;
+    }
+    fprintf (stderr, "Unrecognized option: --%s\n", arg);
+    return FALSE;
+}
+
+/* See command-line-arguments.h for description */
+int
+parse_arguments (int argc, char **argv,
+		 const notmuch_opt_desc_t *options, int opt_index) {
+
+    int pos_arg_index = 0;
+    notmuch_bool_t more_args = TRUE;
+
+    while (more_args && opt_index < argc) {
+	if (strncmp (argv[opt_index],"--",2) != 0) {
+
+	    more_args = parse_position_arg (argv[opt_index], pos_arg_index, options);
+
+	    if (more_args) {
+		pos_arg_index++;
+		opt_index++;
+	    }
+
+	} else {
+
+	    if (strlen (argv[opt_index]) == 2)
+		return opt_index+1;
+
+	    more_args = parse_option (argv[opt_index], options);
+	    if (more_args) {
+		opt_index++;
+	    } else {
+		opt_index = -1;
+	    }
+
+	}
+    }
+
+    return opt_index;
+}

command-line-arguments.h

@@ -0,0 +1,80 @@
+#ifndef NOTMUCH_OPTS_H
+#define NOTMUCH_OPTS_H
+
+#include "notmuch.h"
+
+enum notmuch_opt_type {
+    NOTMUCH_OPT_END = 0,
+    NOTMUCH_OPT_BOOLEAN,	/* --verbose              */
+    NOTMUCH_OPT_INT,		/* --frob=8               */
+    NOTMUCH_OPT_KEYWORD,	/* --format=raw|json|text */
+    NOTMUCH_OPT_STRING,		/* --file=/tmp/gnarf.txt  */
+    NOTMUCH_OPT_POSITION	/* notmuch dump pos_arg   */
+};
+
+/*
+ * Describe one of the possibilities for a keyword option
+ * 'value' will be copied to the output variable
+ */
+
+typedef struct notmuch_keyword {
+    const char *name;
+    int value;
+} notmuch_keyword_t;
+
+/*
+ * Describe one option.
+ *
+ * First two parameters are mandatory.
+ *
+ * name is mandatory _except_ for positional arguments.
+ *
+ * arg_id is currently unused, but could define short arguments.
+ *
+ * keywords is a (possibly NULL) pointer to an array of keywords
+ */
+typedef struct notmuch_opt_desc {
+    enum notmuch_opt_type opt_type;
+    void *output_var;
+    const char *name;
+    int  arg_id;
+    struct notmuch_keyword *keywords;
+} notmuch_opt_desc_t;
+
+
+/*
+  This is the main entry point for command line argument parsing.
+
+  Parse command line arguments according to structure options,
+  starting at position opt_index.
+
+  All output of parsed values is via pointers in options.
+
+  Parsing stops at -- (consumed) or at the (k+1)st argument
+  not starting with -- (a "positional argument") if options contains
+  k positional argument descriptors.
+
+  Returns the index of first non-parsed argument, or -1 in case of error.
+
+*/
+int
+parse_arguments (int argc, char **argv, const notmuch_opt_desc_t *options, int opt_index);
+
+/*
+ * If the argument parsing loop provided by parse_arguments is not
+ * flexible enough, then the user might be interested in the following
+ * routines, but note that the API to parse_option might have to
+ * change. See command-line-arguments.c for descriptions of these
+ * functions.
+ */
+
+notmuch_bool_t
+parse_option (const char *arg, const notmuch_opt_desc_t* options);
+
+notmuch_bool_t
+parse_position_arg (const char *arg,
+		    int position_arg_index,
+		    const notmuch_opt_desc_t* options);
+
+
+#endif

notmuch-client.h

@@ -238,4 +238,5 @@ notmuch_config_set_maildir_synchronize_flags (notmuch_config_t *config,
 notmuch_bool_t
 debugger_is_active (void);
 
+#include "command-line-arguments.h"
 #endif