3 files changed, 129 insertions, 9 deletions

diff --git a/src/select/computed.c b/src/select/computed.c
index 107c884..2d3aea8 100644
--- a/src/select/computed.c
+++ b/src/select/computed.c
@@ -277,23 +277,34 @@ css_error css_computed_style_initialise(css_computed_style *style,
  * \param child              Child style
  * \param compute_font_size  Function to compute an absolute font size
  * \param pw                 Client data for compute_font_size
- * \param result             Pointer to style to compose into
+ * \param result             Updated to point to new composed style
+ *                           Ownership passed to client.
  * \return CSS_OK on success, appropriate error otherwise.
  *
  * \pre \a parent is a fully composed style (thus has no inherited properties)
- *
- * \note \a child and \a result may point at the same object
  */
-css_error css_computed_style_compose(const css_computed_style *parent,
-		css_computed_style *child,
+css_error css_computed_style_compose(
+		const css_computed_style *restrict parent,
+		const css_computed_style *restrict child,
 		css_error (*compute_font_size)(void *pw,
 			const css_hint *parent, css_hint *size),
 		void *pw,
-		css_computed_style **result)
+		css_computed_style **restrict result)
 {
-	css_error error = CSS_OK;
+	css_computed_style *composed;
+	css_error error;
 	size_t i;
 
+	/* TODO:
+	 *   Make this function take a composition context, to allow us
+	 *   to avoid the churn of unnecesaraly allocating and freeing
+	 *   the memory to compose styles into.
+	 */
+	error = css_computed_style_create(&composed);
+	if (error != CSS_OK) {
+		return error;
+	}
+
 	/* Iterate through the properties */
 	for (i = 0; i < CSS_N_PROPERTIES; i++) {
 		/* Skip any in extension blocks if the block does not exist */
@@ -316,18 +327,19 @@ css_error css_computed_style_compose(const css_computed_style *parent,
 		}
 
 		/* Compose the property */
-		error = prop_dispatch[i].compose(parent, child, *result);
+		error = prop_dispatch[i].compose(parent, child, composed);
 		if (error != CSS_OK)
 			break;
 	}
 
 	/* Finally, compute absolute values for everything */
-	error = css__compute_absolute_values(parent, *result,
+	error = css__compute_absolute_values(parent, composed,
 			compute_font_size, pw);
 	if (error != CSS_OK) {
 		return error;
 	}
 
+	*result = composed;
 	return css__arena_intern_style(result);
 }
 
diff --git a/src/select/computed.h b/src/select/computed.h
index f965993..230711d 100644
--- a/src/select/computed.h
+++ b/src/select/computed.h
@@ -325,6 +325,23 @@ struct css_computed_style {
 	uint32_t bin;
 };
 
+
+/**
+ * Take a new reference to a computed style
+ *
+ * \param style  The style to take a new reference to.
+ * \return The new computed style reference
+ */
+static inline css_computed_style * css__computed_style_ref(
+		css_computed_style *style)
+{
+	if (style == NULL)
+		return NULL;
+
+	style->count++;
+	return style;
+}
+
 css_error css__computed_uncommon_destroy(css_computed_uncommon *uncommon);
 
 css_error css__compute_absolute_values(const css_computed_style *parent,
diff --git a/src/select/select.c b/src/select/select.c
index 367c26a..a1ec746 100644
--- a/src/select/select.c
+++ b/src/select/select.c
@@ -15,6 +15,7 @@
 #include "bytecode/bytecode.h"
 #include "bytecode/opcodes.h"
 #include "stylesheet.h"
+#include "select/arena.h"
 #include "select/computed.h"
 #include "select/dispatch.h"
 #include "select/hash.h"
@@ -74,6 +75,9 @@ struct css_select_ctx {
 	lwc_string *first_letter;
 	lwc_string *before;
 	lwc_string *after;
+
+	/* Interned default style */
+	css_computed_style *default_style;
 };
 
 /**
@@ -258,6 +262,9 @@ css_error css_select_ctx_destroy(css_select_ctx *ctx)
 
 	destroy_strings(ctx);
 
+	if (ctx->default_style != NULL)
+		css_computed_style_destroy(ctx->default_style);
+
 	if (ctx->sheets != NULL)
 		free(ctx->sheets);
 
@@ -406,6 +413,78 @@ css_error css_select_ctx_get_sheet(css_select_ctx *ctx, uint32_t index,
 	return CSS_OK;
 }
 
+
+/**
+ * Create a default style on the selection context
+ *
+ * \param ctx		Context to create default style in
+ * \param handler	Dispatch table of handler functions
+ * \param pw		Client-specific private data for handler functions
+ * \return CSS_OK on success, appropriate error otherwise
+ */
+static css_error css__select_ctx_create_default_style(css_select_ctx *ctx,
+		css_select_handler *handler, void *pw)
+{
+	css_computed_style *style;
+	css_error error;
+
+	/* Need to construct the default style */
+	error = css_computed_style_create(&style);
+	if (error != CSS_OK)
+		return error;
+
+	error = css_computed_style_initialise(style, handler, pw);
+	if (error != CSS_OK) {
+		css_computed_style_destroy(style);
+		return error;
+	}
+
+	/* Neither create nor initialise intern the style, so intern it now */
+	error = css__arena_intern_style(&style);
+	if (error != CSS_OK)
+		return error;
+
+	/* Store it on the ctx */
+	ctx->default_style = style;
+
+	return CSS_OK;
+}
+
+
+/**
+ * Get a default style, e.g. for an implied element's anonamous box
+ *
+ * \param ctx		Selection context (used to avoid recreating default)
+ * \param handler	Dispatch table of handler functions
+ * \param pw		Client-specific private data for handler functions
+ * \param style		Pointer to location to receive default style
+ * \return CSS_OK on success, appropriate error otherwise.
+ */
+css_error css_select_default_style(css_select_ctx *ctx,
+		css_select_handler *handler, void *pw,
+		css_computed_style **style)
+{
+	css_error error;
+
+	if (ctx == NULL || style == NULL || handler == NULL ||
+			handler->handler_version !=
+					CSS_SELECT_HANDLER_VERSION_1)
+		return CSS_BADPARM;
+
+	/* Ensure the ctx has a default style */
+	if (ctx->default_style == NULL) {
+		error = css__select_ctx_create_default_style(ctx, handler, pw);
+		if (error != CSS_OK) {
+			return error;
+		}
+	}
+
+	/* Pass a ref back to the client */
+	*style = css__computed_style_ref(ctx->default_style);
+	return CSS_OK;
+}
+
+
 /**
  * Select a style for the given node
  *
@@ -659,6 +738,18 @@ css_error css_select_style(css_select_ctx *ctx, void *node,
 			goto cleanup;
 	}
 
+	/* Intern the partial computed styles */
+	for (j = CSS_PSEUDO_ELEMENT_NONE; j < CSS_PSEUDO_ELEMENT_COUNT; j++) {
+		/* Skip non-existent pseudo elements */
+		if (state.results->styles[j] == NULL)
+			continue;
+
+		error = css__arena_intern_style(&state.results->styles[j]);
+		if (error != CSS_OK) {
+			goto cleanup;
+		}
+	}
+
 	/* Add node name to bloom */
 
 	if (lwc_string_caseless_hash_value(state.element.name,