Changeset 20ac1a4 in mainline

Timestamp:

2012-07-30T02:07:10Z (12 years ago)

Author:

Sean Bartell <wingedtachikoma@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

78d3a00

Parents:

10334c2e

Message:

Bithenge: add syntactic sugar for if in struct

Location:

uspace/app/bithenge

Files:

• expression.c (modified) (1 diff)
• expression.h (modified) (1 diff)
• script.c (modified) (6 diffs)

uspace/app/bithenge/expression.c

@@ -420 +420 @@
         bithenge_transform_t base;
         bithenge_expression_t *expr;
+} expression_transform_t;
+
+static inline bithenge_transform_t *expression_as_transform(
+    expression_transform_t *self)
+{
+        return &self->base;
+}
+
+static inline expression_transform_t *transform_as_expression(
+    bithenge_transform_t *base)
+{
+        return (expression_transform_t *)base;
+}
+
+static int expression_transform_apply(bithenge_transform_t *base,
+    bithenge_scope_t *scope, bithenge_node_t *in, bithenge_node_t **out)
+{
+        expression_transform_t *self = transform_as_expression(base);
+        if (bithenge_node_type(in) != BITHENGE_NODE_BLOB)
+                return EINVAL;
+        aoff64_t len;
+        int rc = bithenge_blob_size(bithenge_node_as_blob(in), &len);
+        if (rc != EOK)
+                return rc;
+        if (len != 0)
+                return EINVAL;
+        return bithenge_expression_evaluate(self->expr, scope, out);
+}
+
+static int expression_transform_prefix_length(bithenge_transform_t *base,
+    bithenge_scope_t *scope, bithenge_blob_t *in, aoff64_t *out)
+{
+        *out = 0;
+        return EOK;
+}
+
+static void expression_transform_destroy(bithenge_transform_t *base)
+{
+        expression_transform_t *self = transform_as_expression(base);
+        bithenge_expression_dec_ref(self->expr);
+        free(self);
+}
+
+static const bithenge_transform_ops_t expression_transform_ops = {
+        .apply = expression_transform_apply,
+        .prefix_length = expression_transform_prefix_length,
+        .destroy = expression_transform_destroy,
+};
+
+/** Create a transform that takes an empty blob and produces the result of an
+ * expression. Takes a reference to the expression.
+ * @param[out] out Holds the new transform.
+ * @param expr The expression to evaluate.
+ * @return EOK on success or an error code from errno.h. */
+int bithenge_expression_transform(bithenge_transform_t ** out,
+    bithenge_expression_t *expr)
+{
+        int rc;
+        expression_transform_t *self = malloc(sizeof(*self));
+        if (!self) {
+                rc = ENOMEM;
+                goto error;
+        }
+
+        rc = bithenge_init_transform(expression_as_transform(self),
+            &expression_transform_ops, 0);
+        if (rc != EOK)
+                goto error;
+
+        self->expr = expr;
+        *out = expression_as_transform(self);
+        return EOK;
+
+error:
+        free(self);
+        bithenge_expression_dec_ref(expr);
+        return rc;
+}
+
+typedef struct {
+        bithenge_transform_t base;
+        bithenge_expression_t *expr;
         bithenge_transform_t *true_xform, *false_xform;
 } if_transform_t;

uspace/app/bithenge/expression.h

@@ -100 +100 @@
 int bithenge_param_wrapper(bithenge_transform_t **, bithenge_transform_t *,
     bithenge_expression_t **);
+int bithenge_expression_transform(bithenge_transform_t **,
+    bithenge_expression_t *);
 int bithenge_if_transform(bithenge_transform_t **, bithenge_expression_t *,
     bithenge_transform_t *, bithenge_transform_t *);

uspace/app/bithenge/script.c

@@ -342 +342 @@
 
 static bithenge_transform_t *parse_transform(state_t *state);
+static bithenge_transform_t *parse_struct(state_t *state);
 
 static bithenge_expression_t *parse_expression(state_t *state)
@@ -490 +491 @@
 }
 
-static bithenge_transform_t *parse_if(state_t *state)
+static bithenge_transform_t *parse_if(state_t *state, bool in_struct)
 {
         expect(state, TOKEN_IF);
@@ -497 +498 @@
         expect(state, ')');
         expect(state, '{');
-        bithenge_transform_t *true_xform = parse_transform(state);
+        bithenge_transform_t *true_xform =
+            in_struct ? parse_struct(state) : parse_transform(state);
         expect(state, '}');
-        expect(state, TOKEN_ELSE);
-        expect(state, '{');
-        bithenge_transform_t *false_xform = parse_transform(state);
-        expect(state, '}');
+        bithenge_transform_t *false_xform = NULL;
+        if (state->token == TOKEN_ELSE) {
+                next_token(state);
+                expect(state, '{');
+                false_xform =
+                    in_struct ? parse_struct(state) : parse_transform(state);
+                expect(state, '}');
+        } else {
+                if (in_struct) {
+                        bithenge_node_t *node;
+                        int rc = bithenge_new_empty_internal_node(&node);
+                        if (rc != EOK) {
+                                error_errno(state, rc);
+                                goto error;
+                        }
+                        bithenge_expression_t *expr;
+                        rc = bithenge_const_expression(&expr, node);
+                        if (rc != EOK) {
+                                error_errno(state, rc);
+                                goto error;
+                        }
+                        rc = bithenge_expression_transform(&false_xform, expr);
+                        if (rc != EOK) {
+                                error_errno(state, rc);
+                                false_xform = NULL;
+                                goto error;
+                        }
+                } else
+                        syntax_error(state, "else expected");
+        }
         if (state->error != EOK) {
+error:
                 bithenge_expression_dec_ref(expr);
                 bithenge_transform_dec_ref(true_xform);
@@ -519 +548 @@
 }
 
+/* The TOKEN_STRUCT and '{' must already have been skipped. */
 static bithenge_transform_t *parse_struct(state_t *state)
 {
@@ -525 +555 @@
         /* We keep an extra space for the {NULL, NULL} terminator. */
         subxforms = state_malloc(state, sizeof(*subxforms));
-        expect(state, TOKEN_STRUCT);
-        expect(state, '{');
         while (state->error == EOK && state->token != '}') {
-                if (state->token == '.') {
-                        expect(state, '.');
-                        subxforms[num].name = expect_identifier(state);
+                if (state->token == TOKEN_IF) {
+                        subxforms[num].transform = parse_if(state, true);
+                        subxforms[num].name = NULL;
+                } else {
+                        if (state->token == '.') {
+                                next_token(state);
+                                subxforms[num].name = expect_identifier(state);
+                        } else {
+                                subxforms[num].name = NULL;
+                        }
                         expect(state, TOKEN_LEFT_ARROW);
-                } else {
-                        subxforms[num].name = NULL;
-                        expect(state, TOKEN_LEFT_ARROW);
-                }
-                subxforms[num].transform = parse_transform(state);
-                expect(state, ';');
+                        subxforms[num].transform = parse_transform(state);
+                        expect(state, ';');
+                }
                 num++;
                 subxforms = state_realloc(state, subxforms,
                     (num + 1)*sizeof(*subxforms));
         }
-        expect(state, '}');
 
         if (state->error != EOK) {
@@ -571 +602 @@
                 return parse_invocation(state);
         } else if (state->token == TOKEN_IF) {
-                return parse_if(state);
+                return parse_if(state, false);
         } else if (state->token == TOKEN_STRUCT) {
-                return parse_struct(state);
+                next_token(state);
+                expect(state, '{');
+                bithenge_transform_t *xform = parse_struct(state);
+                expect(state, '}');
+                return xform;
         } else {
                 syntax_error(state, "unexpected (transform expected)");