Serialization of EO user objects.

eo/src/serial/Parser.cpp

@@ -0,0 +1,153 @@
+# include <map>
+# include <string>
+# include <sstream>
+# include <vector>
+
+# include "Parser.h"
+
+# include "Array.h"
+# include "Object.h"
+# include "String.h"
+
+// in debug mode only
+// # define DEBUG(x) std::cout << x << std::endl;
+# define DEBUG(x)
+
+using namespace eoserial;
+
+namespace eoserial
+{
+
+/**
+ * @brief Parses a string contained between double quotes.
+ *
+ * Strings can contain escaped double quotes.
+ * @param str The string we're parsing.
+ * @param pos The index of current position in parsed string.
+ * This index will be updated so as to allow the parser to
+ * continue.
+ */
+static std::string parseString(const std::string& str, size_t & pos)
+{
+    // example : "hello"
+    // example 2 : "\"world\""
+    // for hello:
+    // firstQuote == 0, secondQuote == 6
+    // sub string should be from firstQuote+1 to secondQuote-1
+    // so its size should be (secondQuote-1 -(firstQuote+1) + 1)
+    std::string value;
+    size_t firstQuote = str.find( '"', pos );
+    size_t secondQuote;
+
+    /* instead of just seeking the second quote, we need to ensure
+    // that there is no escaped quote before this one.
+    // actually this is harder than that. Using backslashes
+    // to escape double quotes mean that backslashes have to be
+    // escaped to.
+    // example : "text\\" to symbolize : text\
+    // example : "text\\\" to symbolize : text\"
+    // In fact, we should find if number of backslashes is odd; in this case,
+    // the double quotes are escaped and we should find the next one.
+    */
+    int backslashesCount;
+    do {
+        ++pos;
+        secondQuote = str.find( '"', pos );
+        size_t i = secondQuote - 1;
+
+        // Find the backslashes
+        backslashesCount = 0;
+        while ( str[ i ] == '\\' )
+        {
+            --i;
+            ++backslashesCount;
+        }
+        pos = secondQuote;
+    } while( backslashesCount % 2 == 1 );
+
+    value = str.substr( firstQuote+1, secondQuote-firstQuote-1 );
+    pos = secondQuote + 1;
+    return value;
+}
+
+/**
+ * @brief Moves the given index pos to the next character which is
+ * neither a coma, a space nor a new line.
+ *
+ * @param str The string in which we want to ignores those characters.
+ * @param pos The index of current position in parsed string.
+ */
+static void ignoreChars(const std::string& str, size_t & pos)
+{
+    // ignore white spaces and comas
+    for (char current = str[ pos ];
+        current == ',' || current == ' ' || current == '\n';
+        current = str[ ++pos ]);
+}
+
+String* Parser::parseJsonString(const std::string & str, size_t & pos)
+{
+    return new String( parseString( str, pos ) );
+}
+
+Object* Parser::parse(const std::string & str)
+{
+    size_t initial(0); // we begin at position 0
+    return static_cast<Object*>( parseRight(str, initial) );
+}
+
+Entity* Parser::parseRight(const std::string & str, size_t & pos)
+{
+    Entity* value = 0;
+
+    if ( str[ pos ] == '{' )
+    {
+        // next one is an object
+        DEBUG("We read an object.")
+        Object* obj = new Object;
+        pos += 1;
+        while( pos < str.size() && str[ pos ] != '}' )
+        {
+            parseLeft( str, pos, obj );
+            ignoreChars( str, pos );
+        }
+        DEBUG("We just finished to read an object ! ")
+        pos += 1; // we're on the }, go to the next char
+        value = obj;
+    }
+    else if ( str[ pos ] == '"' )
+    {
+        // next one is a string
+        DEBUG("We read a string")
+        value = parseJsonString( str, pos );
+    }
+    else if ( str[ pos ] == '[' )
+    {
+        // next one is an array
+        DEBUG("We read an array")
+        Array* array = new Array;
+        pos += 1;
+        while( pos < str.size() && str[ pos ] != ']' )
+        {
+            Entity* child = parseRight( str, pos );
+            if ( child )
+                array->push_back( child );
+        }
+        DEBUG("We've finished to read our array.")
+        pos += 1; // we're on the ], go to the next char
+        value = array;
+    }
+    ignoreChars( str, pos );
+    return value;
+}
+
+void Parser::parseLeft(const std::string & str, size_t & pos, Object* eoserial)
+{
+    std::string key = parseString(str, pos);
+    ++pos; // the colon
+    DEBUG("We've read the key ")
+    (*eoserial)[ key ] = parseRight( str, pos ); 
+}
+
+} // namespace eoserial
+