Diff: JsonParser.h

Revision:

0:d38d192c2f5f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/JsonParser.h	Thu Aug 30 13:20:01 2012 +0000
@@ -0,0 +1,242 @@
+/*
+ * (c) Copyright 2012 EVRYTHNG Ltd London / Zurich
+ * www.evrythng.com
+ *
+ * --- DISCLAIMER ---
+ *
+ * EVRYTHNG provides this source code "as is" and without warranty of any kind,
+ * and hereby disclaims all express or implied warranties, including without
+ * limitation warranties of merchantability, fitness for a particular purpose,
+ * performance, accuracy, reliability, and non-infringement.
+ *
+ * Author: Michel Yerly
+ *
+ */
+#ifndef JSONPARSER_H
+#define JSONPARSER_H
+
+#include <vector>
+#include <map>
+#include <string>
+
+/*
+ * Possible JSON value types
+ */
+enum ValueType {
+
+    VT_DOUBLE,   // Number
+    VT_CHAR_PTR, // String
+    VT_VEC_PTR,  // Array
+    VT_MAP_PTR,  // Object
+    VT_CST_NULL, // Null
+    VT_CST_TRUE, // True
+    VT_CST_FALSE // False
+};
+
+/*
+ * Class to hold a JSON value. A JSON value may be composed of other JSON
+ * values.
+ */
+class JsonValue
+{
+public:
+
+    /*
+     * Creates a new string JSON value. The string is copied into the object.
+     * WARNING: a new object is created. The caller is responsible of deleting
+     * it.
+     * buffer: the string to read from.
+     * len: the number of characters to read.
+     */
+    static JsonValue* createString(const char* buffer, int len);
+    
+    /* Creates a new number JSON value.
+     * WARNING: a new object is created. The caller is responsible of deleting
+     * it.
+     */
+    static JsonValue* createDouble(double d);
+
+    /* Creates a new object JSON value.
+     * WARNING: a new object is created. The caller is responsible of deleting
+     * it.
+     */
+    static JsonValue* createMap();
+
+    /* Creates a new array JSON value.
+     * WARNING: a new object is created. The caller is responsible of deleting
+     * it.
+     */
+    static JsonValue* createVector();
+    
+    /* Creates a new true or false JSON value, depending on b.
+     * WARNING: a new object is created. The caller is responsible of deleting
+     * it.
+     */
+    static JsonValue* createBoolean(bool b);
+    
+    /* Creates a new null JSON value.
+     * WARNING: a new object is created. The caller is responsible of deleting
+     * it.
+     */
+    static JsonValue* createNull();
+
+    /* 
+     * Destructor.
+     * The destructor also deletes nested JsonValues if any.
+     */
+    virtual ~JsonValue();
+
+    /*
+     * Gets a JSON value given a path.
+     * If the path is NULL or an empty string the method returns this.
+     * If there is an error, the method returns NULL.
+     * The path is composed of strings (object keys) and numbers (array 
+     * indices) separated by '/'.
+     *
+     * Example:
+     *   JSON: {"xy":34,"ab":[{"r":true},{"s":false}]}
+     *   Path: ab/1/s
+     *   Returns: a JsonValue representing false.
+     */
+    JsonValue* get(const char* path);
+    
+    /*
+     * Gets a pointer to a double given a path (see get()).
+     * If there is an error, the method returns NULL.
+     */
+    const double* getDouble(const char* path);
+    
+    /*
+     * Gets a pointer to a string given a path (see get()).
+     * If there is an error, the method returns NULL.
+     */
+    const char* getString(const char* path);
+    
+    /*
+     * Gets a pointer to an array given a path (see get()).
+     * If there is an error, the method returns NULL.
+     */
+    const std::vector<JsonValue*>* getVector(const char* path);
+
+    /*
+     * Gets a pointer to a map given a path (see get()).
+     * If there is an error, the method returns NULL.
+     */
+    const std::map<std::string,JsonValue*>* getMap(const char* path);
+
+    /*
+     * Gets a pointer to a boolean given a path (see get()).
+     * If there is an error, the method returns NULL.
+     */
+    const bool* getBoolean(const char* path);
+
+    /*
+     * Determines if the value at the path (see get()) is null.
+     * Return true if and only if the value is explicitely null.
+     */
+    bool isNull(const char* path);
+
+    /*
+     * Debug function.
+     */
+    void print();
+
+    friend class JsonParser;
+
+private:
+
+    /*
+     * Constructor that creates a string JSON value. The string is copied into
+     * the object.
+     * buffer: the string to read from.
+     * len: the number of characters to read.
+     */
+    JsonValue(const char* buffer, int len);
+    
+    /*
+     * Constructor that creates a number JSON value.
+     */
+    JsonValue(double d);
+    
+    /*
+     * Constructor that creates either a True or a False JSON value.
+     */
+    JsonValue(bool b);
+    
+    /*
+     * Constructor that creates a JSON value without specifying the type.
+     */
+    JsonValue();
+    
+    ValueType type;
+    union {
+        double d;
+        char* s;
+        std::vector<JsonValue*>* vec;
+        std::map<std::string,JsonValue*>* map;
+    } value;
+
+};
+
+enum TokenType {
+    TOKEN_EOS,
+    TOKEN_NUMBER,
+    TOKEN_STRING,
+    TOKEN_DELIMITER,
+    TOKEN_TRUE,
+    TOKEN_FALSE,
+    TOKEN_NULL
+};
+
+/*
+ * Class to parse a JSON string.
+ *
+ * NOTE: The current implementation does only support ASCII encoding.
+ */
+class JsonParser
+{
+public:
+
+    /*
+     * Constructor.
+     */
+    JsonParser();
+    
+    /*
+     * Destructor.
+     * The destructor also deletes the parsed document (the one you get with
+     * getDocument().
+     */
+    virtual ~JsonParser();
+    
+    /*
+     * Parses the json string.
+     * json: String that contains the json to parse.
+     * Returns 0 on success, or -1 on error.
+     *
+     * NOTE: This method deletes the previously parsed document.
+     */
+    int parse(const char* json);
+    
+    /*
+     * Returns the parsed document, or NULL if the json is not parsed.
+     */
+    JsonValue* getDocument();
+
+private:
+    const char* json;
+    int json_len;
+    TokenType ct;
+    int ctPos;
+    int ctLen;
+    double ctNumberVal;
+    JsonValue* pDocument;
+
+    int goToNextToken();
+
+    int parseObject(JsonValue** object);
+    int parseValue(JsonValue** value);
+    int parseArray(JsonValue** array);
+};
+
+#endif
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