Changeset 10334c2e in mainline for uspace/app/bithenge/expression.c

Timestamp:

2012-07-30T01:40:55Z (9 years ago)

Author:

Sean Bartell <wingedtachikoma@…>

Branches:

lfn, master

Children:

20ac1a4

Parents:

d1e580a

Message:

Bithenge: add if_transform

File:

• uspace/app/bithenge/expression.c (modified) (1 diff)

uspace/app/bithenge/expression.c

@@ -417 +417 @@
 }
 
+typedef struct {
+        bithenge_transform_t base;
+        bithenge_expression_t *expr;
+        bithenge_transform_t *true_xform, *false_xform;
+} if_transform_t;
+
+static inline bithenge_transform_t *if_as_transform(if_transform_t *self)
+{
+        return &self->base;
+}
+
+static inline if_transform_t *transform_as_if(bithenge_transform_t *base)
+{
+        return (if_transform_t *)base;
+}
+
+static int if_transform_choose(if_transform_t *self, bithenge_scope_t *scope,
+    bool *out)
+{
+        bithenge_node_t *cond_node;
+        int rc = bithenge_expression_evaluate(self->expr, scope, &cond_node);
+        if (rc != EOK)
+                return rc;
+        if (bithenge_node_type(cond_node) != BITHENGE_NODE_BOOLEAN) {
+                bithenge_node_dec_ref(cond_node);
+                return EINVAL;
+        }
+        *out = bithenge_boolean_node_value(cond_node);
+        bithenge_node_dec_ref(cond_node);
+        return EOK;
+}
+
+static int if_transform_apply(bithenge_transform_t *base,
+    bithenge_scope_t *scope, bithenge_node_t *in, bithenge_node_t **out)
+{
+        if_transform_t *self = transform_as_if(base);
+        bool cond;
+        int rc = if_transform_choose(self, scope, &cond);
+        if (rc != EOK)
+                return rc;
+        return bithenge_transform_apply(
+            cond ? self->true_xform : self->false_xform, scope, in, out);
+}
+
+static int if_transform_prefix_length(bithenge_transform_t *base,
+    bithenge_scope_t *scope, bithenge_blob_t *in, aoff64_t *out)
+{
+        if_transform_t *self = transform_as_if(base);
+        bool cond;
+        int rc = if_transform_choose(self, scope, &cond);
+        if (rc != EOK)
+                return rc;
+        return bithenge_transform_prefix_length(
+            cond ? self->true_xform : self->false_xform, scope, in, out);
+}
+
+static void if_transform_destroy(bithenge_transform_t *base)
+{
+        if_transform_t *self = transform_as_if(base);
+        bithenge_expression_dec_ref(self->expr);
+        bithenge_transform_dec_ref(self->true_xform);
+        bithenge_transform_dec_ref(self->false_xform);
+        free(self);
+}
+
+static const bithenge_transform_ops_t if_transform_ops = {
+        .apply = if_transform_apply,
+        .prefix_length = if_transform_prefix_length,
+        .destroy = if_transform_destroy,
+};
+
+/** Create a transform that applies either of two transforms depending on a
+ * boolean expression. Takes references to @a expr, @a true_xform, and
+ * @a false_xform.
+ * @param[out] out Holds the new transform.
+ * @param expr The boolean expression to evaluate.
+ * @param true_xform The transform to apply if the expression is true.
+ * @param false_xform The transform to apply if the expression is false. */
+int bithenge_if_transform(bithenge_transform_t **out,
+    bithenge_expression_t *expr, bithenge_transform_t *true_xform,
+    bithenge_transform_t *false_xform)
+{
+        int rc;
+        if_transform_t *self = malloc(sizeof(*self));
+        if (!self) {
+                rc = ENOMEM;
+                goto error;
+        }
+
+        rc = bithenge_init_transform(if_as_transform(self), &if_transform_ops,
+            0);
+        if (rc != EOK)
+                goto error;
+
+        self->expr = expr;
+        self->true_xform = true_xform;
+        self->false_xform = false_xform;
+        *out = if_as_transform(self);
+        return EOK;
+
+error:
+        free(self);
+        bithenge_expression_dec_ref(expr);
+        bithenge_transform_dec_ref(true_xform);
+        bithenge_transform_dec_ref(false_xform);
+        return rc;
+}
+
 /** @}
  */