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Diffstat (limited to 'webcam/com/adobe/serialization/json/JSONTokenizer.as')
| -rw-r--r-- | webcam/com/adobe/serialization/json/JSONTokenizer.as | 550 |
1 files changed, 550 insertions, 0 deletions
diff --git a/webcam/com/adobe/serialization/json/JSONTokenizer.as b/webcam/com/adobe/serialization/json/JSONTokenizer.as new file mode 100644 index 0000000..2516446 --- /dev/null +++ b/webcam/com/adobe/serialization/json/JSONTokenizer.as @@ -0,0 +1,550 @@ +/*
+Adobe Systems Incorporated(r) Source Code License Agreement
+Copyright(c) 2005 Adobe Systems Incorporated. All rights reserved.
+
+Please read this Source Code License Agreement carefully before using
+the source code.
+
+Adobe Systems Incorporated grants to you a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable copyright license, to reproduce,
+prepare derivative works of, publicly display, publicly perform, and
+distribute this source code and such derivative works in source or
+object code form without any attribution requirements.
+
+The name "Adobe Systems Incorporated" must not be used to endorse or promote products
+derived from the source code without prior written permission.
+
+You agree to indemnify, hold harmless and defend Adobe Systems Incorporated from and
+against any loss, damage, claims or lawsuits, including attorney's
+fees that arise or result from your use or distribution of the source
+code.
+
+THIS SOURCE CODE IS PROVIDED "AS IS" AND "WITH ALL FAULTS", WITHOUT
+ANY TECHNICAL SUPPORT OR ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING,
+BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+FOR A PARTICULAR PURPOSE ARE DISCLAIMED. ALSO, THERE IS NO WARRANTY OF
+NON-INFRINGEMENT, TITLE OR QUIET ENJOYMENT. IN NO EVENT SHALL MACROMEDIA
+OR ITS SUPPLIERS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOURCE CODE, EVEN IF
+ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+package com.adobe.serialization.json {
+
+ public class JSONTokenizer {
+
+ /** The object that will get parsed from the JSON string */
+ private var obj:Object;
+
+ /** The JSON string to be parsed */
+ private var jsonString:String;
+
+ /** The current parsing location in the JSON string */
+ private var loc:int;
+
+ /** The current character in the JSON string during parsing */
+ private var ch:String;
+
+ /**
+ * Constructs a new JSONDecoder to parse a JSON string
+ * into a native object.
+ *
+ * @param s The JSON string to be converted
+ * into a native object
+ */
+ public function JSONTokenizer( s:String ) {
+ jsonString = s;
+ loc = 0;
+
+ // prime the pump by getting the first character
+ nextChar();
+ }
+
+ /**
+ * Gets the next token in the input sting and advances
+ * the character to the next character after the token
+ */
+ public function getNextToken():JSONToken {
+ var token:JSONToken = new JSONToken();
+
+ // skip any whitespace / comments since the last
+ // token was read
+ skipIgnored();
+
+ // examine the new character and see what we have...
+ switch ( ch ) {
+
+ case '{':
+ token.type = JSONTokenType.LEFT_BRACE;
+ token.value = '{';
+ nextChar();
+ break
+
+ case '}':
+ token.type = JSONTokenType.RIGHT_BRACE;
+ token.value = '}';
+ nextChar();
+ break
+
+ case '[':
+ token.type = JSONTokenType.LEFT_BRACKET;
+ token.value = '[';
+ nextChar();
+ break
+
+ case ']':
+ token.type = JSONTokenType.RIGHT_BRACKET;
+ token.value = ']';
+ nextChar();
+ break
+
+ case ',':
+ token.type = JSONTokenType.COMMA;
+ token.value = ',';
+ nextChar();
+ break
+
+ case ':':
+ token.type = JSONTokenType.COLON;
+ token.value = ':';
+ nextChar();
+ break;
+
+ case 't': // attempt to read true
+ var possibleTrue:String = "t" + nextChar() + nextChar() + nextChar();
+
+ if ( possibleTrue == "true" ) {
+ token.type = JSONTokenType.TRUE;
+ token.value = true;
+ nextChar();
+ } else {
+ parseError( "Expecting 'true' but found " + possibleTrue );
+ }
+
+ break;
+
+ case 'f': // attempt to read false
+ var possibleFalse:String = "f" + nextChar() + nextChar() + nextChar() + nextChar();
+
+ if ( possibleFalse == "false" ) {
+ token.type = JSONTokenType.FALSE;
+ token.value = false;
+ nextChar();
+ } else {
+ parseError( "Expecting 'false' but found " + possibleFalse );
+ }
+
+ break;
+
+ case 'n': // attempt to read null
+
+ var possibleNull:String = "n" + nextChar() + nextChar() + nextChar();
+
+ if ( possibleNull == "null" ) {
+ token.type = JSONTokenType.NULL;
+ token.value = null;
+ nextChar();
+ } else {
+ parseError( "Expecting 'null' but found " + possibleNull );
+ }
+
+ break;
+
+ case '"': // the start of a string
+ token = readString();
+ break;
+
+ default:
+ // see if we can read a number
+ if ( isDigit( ch ) || ch == '-' ) {
+ token = readNumber();
+ } else if ( ch == '' ) {
+ // check for reading past the end of the string
+ return null;
+ } else {
+ // not sure what was in the input string - it's not
+ // anything we expected
+ parseError( "Unexpected " + ch + " encountered" );
+ }
+ }
+
+ return token;
+ }
+
+ /**
+ * Attempts to read a string from the input string. Places
+ * the character location at the first character after the
+ * string. It is assumed that ch is " before this method is called.
+ *
+ * @return the JSONToken with the string value if a string could
+ * be read. Throws an error otherwise.
+ */
+ private function readString():JSONToken {
+ // the token for the string we'll try to read
+ var token:JSONToken = new JSONToken();
+ token.type = JSONTokenType.STRING;
+
+ // the string to store the string we'll try to read
+ var string:String = "";
+
+ // advance past the first "
+ nextChar();
+
+ while ( ch != '"' && ch != '' ) {
+
+ // unescape the escape sequences in the string
+ if ( ch == '\\' ) {
+
+ // get the next character so we know what
+ // to unescape
+ nextChar();
+
+ switch ( ch ) {
+
+ case '"': // quotation mark
+ string += '"';
+ break;
+
+ case '/': // solidus
+ string += "/";
+ break;
+
+ case '\\': // reverse solidus
+ string += '\\';
+ break;
+
+ case 'b': // bell
+ string += '\b';
+ break;
+
+ case 'f': // form feed
+ string += '\f';
+ break;
+
+ case 'n': // newline
+ string += '\n';
+ break;
+
+ case 'r': // carriage return
+ string += '\r';
+ break;
+
+ case 't': // horizontal tab
+ string += '\t'
+ break;
+
+ case 'u':
+ // convert a unicode escape sequence
+ // to it's character value - expecting
+ // 4 hex digits
+
+ // save the characters as a string we'll convert to an int
+ var hexValue:String = "";
+
+ // try to find 4 hex characters
+ for ( var i:int = 0; i < 4; i++ ) {
+ // get the next character and determine
+ // if it's a valid hex digit or not
+ if ( !isHexDigit( nextChar() ) ) {
+ parseError( " Excepted a hex digit, but found: " + ch );
+ }
+ // valid, add it to the value
+ hexValue += ch;
+ }
+
+ // convert hexValue to an integer, and use that
+ // integrer value to create a character to add
+ // to our string.
+ string += String.fromCharCode( parseInt( hexValue, 16 ) );
+
+ break;
+
+ default:
+ // couldn't unescape the sequence, so just
+ // pass it through
+ string += '\\' + ch;
+
+ }
+
+ } else {
+ // didn't have to unescape, so add the character to the string
+ string += ch;
+
+ }
+
+ // move to the next character
+ nextChar();
+
+ }
+
+ // we read past the end of the string without closing it, which
+ // is a parse error
+ if ( ch == '' ) {
+ parseError( "Unterminated string literal" );
+ }
+
+ // move past the closing " in the input string
+ nextChar();
+
+ // attach to the string to the token so we can return it
+ token.value = string;
+
+ return token;
+ }
+
+ /**
+ * Attempts to read a number from the input string. Places
+ * the character location at the first character after the
+ * number.
+ *
+ * @return The JSONToken with the number value if a number could
+ * be read. Throws an error otherwise.
+ */
+ private function readNumber():JSONToken {
+ // the token for the number we'll try to read
+ var token:JSONToken = new JSONToken();
+ token.type = JSONTokenType.NUMBER;
+
+ // the string to accumulate the number characters
+ // into that we'll convert to a number at the end
+ var input:String = "";
+
+ // check for a negative number
+ if ( ch == '-' ) {
+ input += '-';
+ nextChar();
+ }
+
+ // the number must start with a digit
+ if ( !isDigit( ch ) )
+ {
+ parseError( "Expecting a digit" );
+ }
+
+ // 0 can only be the first digit if it
+ // is followed by a decimal point
+ if ( ch == '0' )
+ {
+ input += ch;
+ nextChar();
+
+ // make sure no other digits come after 0
+ if ( isDigit( ch ) )
+ {
+ parseError( "A digit cannot immediately follow 0" );
+ }
+ }
+ else
+ {
+ // read numbers while we can
+ while ( isDigit( ch ) ) {
+ input += ch;
+ nextChar();
+ }
+ }
+
+ // check for a decimal value
+ if ( ch == '.' ) {
+ input += '.';
+ nextChar();
+
+ // after the decimal there has to be a digit
+ if ( !isDigit( ch ) )
+ {
+ parseError( "Expecting a digit" );
+ }
+
+ // read more numbers to get the decimal value
+ while ( isDigit( ch ) ) {
+ input += ch;
+ nextChar();
+ }
+ }
+
+ // check for scientific notation
+ if ( ch == 'e' || ch == 'E' )
+ {
+ input += "e"
+ nextChar();
+ // check for sign
+ if ( ch == '+' || ch == '-' )
+ {
+ input += ch;
+ nextChar();
+ }
+
+ // require at least one number for the exponent
+ // in this case
+ if ( !isDigit( ch ) )
+ {
+ parseError( "Scientific notation number needs exponent value" );
+ }
+
+ // read in the exponent
+ while ( isDigit( ch ) )
+ {
+ input += ch;
+ nextChar();
+ }
+ }
+
+ // convert the string to a number value
+ var num:Number = Number( input );
+
+ if ( isFinite( num ) && !isNaN( num ) ) {
+ token.value = num;
+ return token;
+ } else {
+ parseError( "Number " + num + " is not valid!" );
+ }
+ return null;
+ }
+
+ /**
+ * Reads the next character in the input
+ * string and advances the character location.
+ *
+ * @return The next character in the input string, or
+ * null if we've read past the end.
+ */
+ private function nextChar():String {
+ return ch = jsonString.charAt( loc++ );
+ }
+
+ /**
+ * Advances the character location past any
+ * sort of white space and comments
+ */
+ private function skipIgnored():void {
+ skipWhite();
+ skipComments();
+ skipWhite();
+ }
+
+ /**
+ * Skips comments in the input string, either
+ * single-line or multi-line. Advances the character
+ * to the first position after the end of the comment.
+ */
+ private function skipComments():void {
+ if ( ch == '/' ) {
+ // Advance past the first / to find out what type of comment
+ nextChar();
+ switch ( ch ) {
+ case '/': // single-line comment, read through end of line
+
+ // Loop over the characters until we find
+ // a newline or until there's no more characters left
+ do {
+ nextChar();
+ } while ( ch != '\n' && ch != '' )
+
+ // move past the \n
+ nextChar();
+
+ break;
+
+ case '*': // multi-line comment, read until closing */
+
+ // move past the opening *
+ nextChar();
+
+ // try to find a trailing */
+ while ( true ) {
+ if ( ch == '*' ) {
+ // check to see if we have a closing /
+ nextChar();
+ if ( ch == '/') {
+ // move past the end of the closing */
+ nextChar();
+ break;
+ }
+ } else {
+ // move along, looking if the next character is a *
+ nextChar();
+ }
+
+ // when we're here we've read past the end of
+ // the string without finding a closing */, so error
+ if ( ch == '' ) {
+ parseError( "Multi-line comment not closed" );
+ }
+ }
+
+ break;
+
+ // Can't match a comment after a /, so it's a parsing error
+ default:
+ parseError( "Unexpected " + ch + " encountered (expecting '/' or '*' )" );
+ }
+ }
+
+ }
+
+
+ /**
+ * Skip any whitespace in the input string and advances
+ * the character to the first character after any possible
+ * whitespace.
+ */
+ private function skipWhite():void {
+
+ // As long as there are spaces in the input
+ // stream, advance the current location pointer
+ // past them
+ while ( isWhiteSpace( ch ) ) {
+ nextChar();
+ }
+
+ }
+
+ /**
+ * Determines if a character is whitespace or not.
+ *
+ * @return True if the character passed in is a whitespace
+ * character
+ */
+ private function isWhiteSpace( ch:String ):Boolean {
+ return ( ch == ' ' || ch == '\t' || ch == '\n' );
+ }
+
+ /**
+ * Determines if a character is a digit [0-9].
+ *
+ * @return True if the character passed in is a digit
+ */
+ private function isDigit( ch:String ):Boolean {
+ return ( ch >= '0' && ch <= '9' );
+ }
+
+ /**
+ * Determines if a character is a digit [0-9].
+ *
+ * @return True if the character passed in is a digit
+ */
+ private function isHexDigit( ch:String ):Boolean {
+ // get the uppercase value of ch so we only have
+ // to compare the value between 'A' and 'F'
+ var uc:String = ch.toUpperCase();
+
+ // a hex digit is a digit of A-F, inclusive ( using
+ // our uppercase constraint )
+ return ( isDigit( ch ) || ( uc >= 'A' && uc <= 'F' ) );
+ }
+
+ /**
+ * Raises a parsing error with a specified message, tacking
+ * on the error location and the original string.
+ *
+ * @param message The message indicating why the error occurred
+ */
+ public function parseError( message:String ):void {
+ throw new JSONParseError( message, loc, jsonString );
+ }
+ }
+
+}
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