Clean up support for AWK_SCALAR and AWK_VALUE_COOKIE.

3 files changed, 48 insertions, 36 deletions

diff --git a/ChangeLog b/ChangeLog
index 2ebb17de..60e560af 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,21 @@
+2012-07-17         Andrew J. Schorr     <aschorr@telemetry-investments.com>
+
+	* gawkapi.h: Add comments explaining new api_create_value and
+	api_release_value functions.
+	* gawkapi.c (sym_update_real): Allow updates with AWK_SCALAR and
+	AWK_VALUE_COOKIE types.  After creating a regular variable,
+	remove the call to unref(node->var_value), since this is not
+	done elsewhere in the code (see, for example, main.c:init_vars).
+	If the update is for an existing variable, allow any val_type
+	except AWK_ARRAY (was previously disallowing AWK_SCALAR and
+	AWK_VALUE_COOKIE for no apparent reason).
+	(api_sym_update_scalar): The switch should return false for an
+	invalid val_type value, so change the AWK_ARRAY case to default.
+	(valid_subscript_type): Any scalar value is good, so accept any valid
+	type except AWK_ARRAY.
+	(api_create_value): Accept only AWK_NUMBER and AWK_STRING values.
+	Anything else should fail.
+
 2012-07-17         Arnold D. Robbins     <arnold@skeeve.com>
 
 	Speedup:
diff --git a/gawkapi.c b/gawkapi.c
index c750f064..50ebc457 100644
--- a/gawkapi.c
+++ b/gawkapi.c
@@ -495,6 +495,8 @@ sym_update_real(awk_ext_id_t id,
 	case AWK_STRING:
 	case AWK_UNDEFINED:
 	case AWK_ARRAY:
+	case AWK_SCALAR:
+	case AWK_VALUE_COOKIE:
 		break;
 
 	default:
@@ -517,7 +519,6 @@ sym_update_real(awk_ext_id_t id,
 			/* regular variable */
 			node = install_symbol(estrdup((char *) name, strlen(name)),
 					Node_var);
-			unref(node->var_value);
 			node->var_value = awk_value_to_node(value);
 			if (is_const)
 				node->var_assign = set_constant;
@@ -525,31 +526,18 @@ sym_update_real(awk_ext_id_t id,
 		return true;
 	}
 
-	/* if we get here, then it exists already */
-	switch (value->val_type) {
-	case AWK_SCALAR:
-		return false;
-
-	case AWK_STRING:
-	case AWK_NUMBER:
-	case AWK_UNDEFINED:
-		if (node->type == Node_var || node->type == Node_var_new) {
-			unref(node->var_value);
-			node->var_value = awk_value_to_node(value);
-			/* let the extension change its own variable */
-			if (is_const)
-				node->var_assign = set_constant;
-		} else {
-			return false;
-		}
-		break;
-
-	case AWK_ARRAY:
-	case AWK_VALUE_COOKIE:
-		return false;	/* not allowed */
+	/* If we get here, then it exists already.  Any valid type is
+	 * OK except for AWK_ARRAY. */
+	if ((value->val_type != AWK_ARRAY) &&
+		(node->type == Node_var || node->type == Node_var_new)) {
+		unref(node->var_value);
+		node->var_value = awk_value_to_node(value);
+		/* let the extension change its own variable */
+		if (is_const)
+			node->var_assign = set_constant;
+		return true;
 	}
-
-	return true;
+	return false;
 }
 
 /* api_sym_update --- update a symbol, non-constant */
@@ -629,7 +617,7 @@ api_sym_update_scalar(awk_ext_id_t id,
 			return true;
 		}
 		break;
-	case AWK_ARRAY:
+	default:	/* reject AWK_ARRAY or an invalid type */
 		return false;
 		break;
 	}
@@ -643,9 +631,8 @@ api_sym_update_scalar(awk_ext_id_t id,
 }
 
 /*
- * Test if a type is allowed for an array subscript.  A string or numeric
- * value is fine, and undefined is equivalent to "", so those are OK.
- * We reject AWK_ARRAY and AWK_SCALAR.
+ * Test if a type is allowed for an array subscript.
+ * Any scalar value is fine, so only AWK_ARRAY (or an invalid type) is illegal.
  */
 static inline int
 valid_subscript_type(awk_valtype_t valtype)
@@ -654,13 +641,12 @@ valid_subscript_type(awk_valtype_t valtype)
 	case AWK_UNDEFINED:
 	case AWK_NUMBER:
 	case AWK_STRING:
+	case AWK_SCALAR:
 	case AWK_VALUE_COOKIE:
 		return true;
-	case AWK_SCALAR:
-	case AWK_ARRAY:
+	default:	/* AWK_ARRAY or an invalid type */
 		return false;
 	}
-	return false;
 }
 
 /* Array management */
@@ -934,11 +920,8 @@ api_create_value(awk_ext_id_t id, awk_value_t *value,
 	switch (value->val_type) {
 	case AWK_NUMBER:
 	case AWK_STRING:
-	case AWK_UNDEFINED:
 		break;
-	case AWK_ARRAY:
-	case AWK_SCALAR:
-	case AWK_VALUE_COOKIE:
+	default:
 		/* reject anything other than a simple scalar */
 		return false;
 	}
diff --git a/gawkapi.h b/gawkapi.h
index 29631cdd..5d9936fb 100644
--- a/gawkapi.h
+++ b/gawkapi.h
@@ -421,9 +421,20 @@ typedef struct gawk_api {
 			awk_array_t a_cookie,
 			awk_flat_array_t *data);
 
+	/*
+	 * Cache a string or numeric value for efficient later assignment.
+	 * This improves performance when you want to assign the same value
+	 * to one or more variables repeatedly.  Only AWK_NUMBER and AWK_STRING
+	 * values are allowed.  Any other type is rejected.  We disallow
+	 * AWK_UNDEFINED since that case would result in inferior performance.
+	 */
 	awk_bool_t (*api_create_value)(awk_ext_id_t id, awk_value_t *value,
 		    awk_value_cookie_t *result);
 
+	/*
+	 * Release the memory associated with a cookie from api_create_value.
+	 * Please call this to free memory when the value is no longer needed.
+	 */
 	awk_bool_t (*api_release_value)(awk_ext_id_t id, awk_value_cookie_t vc);
 } gawk_api_t;