From 0c80c384756a48d5f731eeafa62b6cd5f3861749 Mon Sep 17 00:00:00 2001
From: Joshua Haberman <joshua@reverberate.org>
Date: Mon, 25 May 2009 18:31:27 -0700
Subject: A flurry of activity.  Doesn't compile yet.

- a descriptor.c that describes the data structures in
  descriptor.proto using the data structures in descriptor.h.
- everything renamed pbstream -> upb.
- modularization rethought.
- Doesn't compile yet, but should once things settle back down.
---
 upb_fieldmap.h | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 upb_fieldmap.h

(limited to 'upb_fieldmap.h')

diff --git a/upb_fieldmap.h b/upb_fieldmap.h
new file mode 100644
index 0000000..0fb5a3e
--- /dev/null
+++ b/upb_fieldmap.h
@@ -0,0 +1,53 @@
+/*
+ * upb - a minimalist implementation of protocol buffers.
+ *
+ * Copyright (c) 2009 Joshua Haberman.  See LICENSE for details.
+ *
+ * A fieldmap is a data structure that supports fast lookup of fields by
+ * number.  It is logically a map of {field_number -> <field info>}, where
+ * <field info> is any struct that begins with the field number.  Fast lookup
+ * is important, because it is in the critical path of parsing. */
+
+#ifndef UPB_FIELDMAP_H_
+#define UPB_FIELDMAP_H_
+
+#include "upb.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct upb_fieldmap {
+  int array_size;
+  void *array;
+  /* TODO: the hashtable part. */
+};
+
+/* Takes an array of num_fields fields and builds an optimized table for fast
+ * lookup of fields by number.  The input fields need not be sorted.  This
+ * fieldmap must be freed with upb_free_fieldmap(). */
+void upb_init_fieldmap(struct upb_fieldmap *fieldmap,
+                       void *fields,
+                       int num_fields,
+                       int field_size);
+void upb_free_fieldmap(struct upb_fieldmap *fieldmap);
+
+/* Looks the given field number up in the fieldmap, and returns the
+ * corresponding field definition (or NULL if this field number does not exist
+ * in this fieldmap). */
+inline void *upb_fieldmap_find(struct upb_fieldmap *fm,
+                               upb_field_number_t num,
+                               size_t info_size)
+{
+  if (num < array_size) {
+    return (char*)fs->array + (num*info_size);
+  } else {
+    /* TODO: the hashtable part. */
+  }
+}
+
+#ifdef __cplusplus
+}  /* extern "C" */
+#endif
+
+#endif  /* UPB_PARSE_H_ */
-- 
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