#region Header
/**
* Lexer.cs
* JSON lexer implementation based on a finite state machine.
*
* The authors disclaim copyright to this source code. For more details, see
* the COPYING file included with this distribution.
**/
#endregion
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
namespace LitJson{
internal class FsmContext
{
public bool Return;
public int NextState;
public Lexer L;
public int StateStack;
}
internal class Lexer
{
#region Fields
private delegate bool StateHandler (FsmContext ctx);
private static int[] fsm_return_table;
private static StateHandler[] fsm_handler_table;
private bool allow_comments;
private bool allow_single_quoted_strings;
private bool end_of_input;
private FsmContext fsm_context;
private int input_buffer;
private int input_char;
private TextReader reader;
private int state;
private StringBuilder string_buffer;
private string string_value;
private int token;
private int unichar;
#endregion
#region Properties
public bool AllowComments {
get { return allow_comments; }
set { allow_comments = value; }
}
public bool AllowSingleQuotedStrings {
get { return allow_single_quoted_strings; }
set { allow_single_quoted_strings = value; }
}
public bool EndOfInput {
get { return end_of_input; }
}
public int Token {
get { return token; }
}
public string StringValue {
get { return string_value; }
}
#endregion
#region Constructors
static Lexer ()
{
PopulateFsmTables ();
}
public Lexer (TextReader reader)
{
allow_comments = true;
allow_single_quoted_strings = true;
input_buffer = 0;
string_buffer = new StringBuilder (128);
state = 1;
end_of_input = false;
this.reader = reader;
fsm_context = new FsmContext ();
fsm_context.L = this;
}
#endregion
#region Static Methods
private static int HexValue (int digit)
{
switch (digit) {
case 'a':
case 'A':
return 10;
case 'b':
case 'B':
return 11;
case 'c':
case 'C':
return 12;
case 'd':
case 'D':
return 13;
case 'e':
case 'E':
return 14;
case 'f':
case 'F':
return 15;
default:
return digit - '0';
}
}
private static void PopulateFsmTables ()
{
fsm_handler_table = new StateHandler[28] {
State1,
State2,
State3,
State4,
State5,
State6,
State7,
State8,
State9,
State10,
State11,
State12,
State13,
State14,
State15,
State16,
State17,
State18,
State19,
State20,
State21,
State22,
State23,
State24,
State25,
State26,
State27,
State28
};
fsm_return_table = new int[28] {
(int) ParserToken.Char,
0,
(int) ParserToken.Number,
(int) ParserToken.Number,
0,
(int) ParserToken.Number,
0,
(int) ParserToken.Number,
0,
0,
(int) ParserToken.True,
0,
0,
0,
(int) ParserToken.False,
0,
0,
(int) ParserToken.Null,
(int) ParserToken.CharSeq,
(int) ParserToken.Char,
0,
0,
(int) ParserToken.CharSeq,
(int) ParserToken.Char,
0,
0,
0,
0
};
}
private static char ProcessEscChar (int esc_char)
{
switch (esc_char) {
case '"':
case '\'':
case '\\':
case '/':
return Convert.ToChar (esc_char);
case 'n':
return '\n';
case 't':
return '\t';
case 'r':
return '\r';
case 'b':
return '\b';
case 'f':
return '\f';
default:
// Unreachable
return '?';
}
}
private static bool State1 (FsmContext ctx)
{
while (ctx.L.GetChar ()) {
if (ctx.L.input_char == ' ' ||
ctx.L.input_char >= '\t' && ctx.L.input_char <= '\r')
continue;
if (ctx.L.input_char >= '1' && ctx.L.input_char <= '9') {
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 3;
return true;
}
switch (ctx.L.input_char) {
case '"':
ctx.NextState = 19;
ctx.Return = true;
return true;
case ',':
case ':':
case '[':
case ']':
case '{':
case '}':
ctx.NextState = 1;
ctx.Return = true;
return true;
case '-':
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 2;
return true;
case '0':
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 4;
return true;
case 'f':
ctx.NextState = 12;
return true;
case 'n':
ctx.NextState = 16;
return true;
case 't':
ctx.NextState = 9;
return true;
case '\'':
if (! ctx.L.allow_single_quoted_strings)
return false;
ctx.L.input_char = '"';
ctx.NextState = 23;
ctx.Return = true;
return true;
case '/':
if (! ctx.L.allow_comments)
return false;
ctx.NextState = 25;
return true;
default:
return false;
}
}
return true;
}
private static bool State2 (FsmContext ctx)
{
ctx.L.GetChar ();
if (ctx.L.input_char >= '1' && ctx.L.input_char<= '9') {
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 3;
return true;
}
switch (ctx.L.input_char) {
case '0':
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 4;
return true;
default:
return false;
}
}
private static bool State3 (FsmContext ctx)
{
while (ctx.L.GetChar ()) {
if (ctx.L.input_char >= '0' && ctx.L.input_char <= '9') {
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
continue;
}
if (ctx.L.input_char == ' ' ||
ctx.L.input_char >= '\t' && ctx.L.input_char <= '\r') {
ctx.Return = true;
ctx.NextState = 1;
return true;
}
switch (ctx.L.input_char) {
case ',':
case ']':
case '}':
ctx.L.UngetChar ();
ctx.Return = true;
ctx.NextState = 1;
return true;
case '.':
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 5;
return true;
case 'e':
case 'E':
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 7;
return true;
default:
return false;
}
}
return true;
}
private static bool State4 (FsmContext ctx)
{
ctx.L.GetChar ();
if (ctx.L.input_char == ' ' ||
ctx.L.input_char >= '\t' && ctx.L.input_char <= '\r') {
ctx.Return = true;
ctx.NextState = 1;
return true;
}
switch (ctx.L.input_char) {
case ',':
case ']':
case '}':
ctx.L.UngetChar ();
ctx.Return = true;
ctx.NextState = 1;
return true;
case '.':
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 5;
return true;
case 'e':
case 'E':
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 7;
return true;
default:
return false;
}
}
private static bool State5 (FsmContext ctx)
{
ctx.L.GetChar ();
if (ctx.L.input_char >= '0' && ctx.L.input_char <= '9') {
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 6;
return true;
}
return false;
}
private static bool State6 (FsmContext ctx)
{
while (ctx.L.GetChar ()) {
if (ctx.L.input_char >= '0' && ctx.L.input_char <= '9') {
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
continue;
}
if (ctx.L.input_char == ' ' ||
ctx.L.input_char >= '\t' && ctx.L.input_char <= '\r') {
ctx.Return = true;
ctx.NextState = 1;
return true;
}
switch (ctx.L.input_char) {
case ',':
case ']':
case '}':
ctx.L.UngetChar ();
ctx.Return = true;
ctx.NextState = 1;
return true;
case 'e':
case 'E':
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 7;
return true;
default:
return false;
}
}
return true;
}
private static bool State7 (FsmContext ctx)
{
ctx.L.GetChar ();
if (ctx.L.input_char >= '0' && ctx.L.input_char<= '9') {
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 8;
return true;
}
switch (ctx.L.input_char) {
case '+':
case '-':
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
ctx.NextState = 8;
return true;
default:
return false;
}
}
private static bool State8 (FsmContext ctx)
{
while (ctx.L.GetChar ()) {
if (ctx.L.input_char >= '0' && ctx.L.input_char<= '9') {
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
continue;
}
if (ctx.L.input_char == ' ' ||
ctx.L.input_char >= '\t' && ctx.L.input_char<= '\r') {
ctx.Return = true;
ctx.NextState = 1;
return true;
}
switch (ctx.L.input_char) {
case ',':
case ']':
case '}':
ctx.L.UngetChar ();
ctx.Return = true;
ctx.NextState = 1;
return true;
default:
return false;
}
}
return true;
}
private static bool State9 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case 'r':
ctx.NextState = 10;
return true;
default:
return false;
}
}
private static bool State10 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case 'u':
ctx.NextState = 11;
return true;
default:
return false;
}
}
private static bool State11 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case 'e':
ctx.Return = true;
ctx.NextState = 1;
return true;
default:
return false;
}
}
private static bool State12 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case 'a':
ctx.NextState = 13;
return true;
default:
return false;
}
}
private static bool State13 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case 'l':
ctx.NextState = 14;
return true;
default:
return false;
}
}
private static bool State14 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case 's':
ctx.NextState = 15;
return true;
default:
return false;
}
}
private static bool State15 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case 'e':
ctx.Return = true;
ctx.NextState = 1;
return true;
default:
return false;
}
}
private static bool State16 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case 'u':
ctx.NextState = 17;
return true;
default:
return false;
}
}
private static bool State17 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case 'l':
ctx.NextState = 18;
return true;
default:
return false;
}
}
private static bool State18 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case 'l':
ctx.Return = true;
ctx.NextState = 1;
return true;
default:
return false;
}
}
private static bool State19 (FsmContext ctx)
{
while (ctx.L.GetChar ()) {
switch (ctx.L.input_char) {
case '"':
ctx.L.UngetChar ();
ctx.Return = true;
ctx.NextState = 20;
return true;
case '\\':
ctx.StateStack = 19;
ctx.NextState = 21;
return true;
default:
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
continue;
}
}
return true;
}
private static bool State20 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case '"':
ctx.Return = true;
ctx.NextState = 1;
return true;
default:
return false;
}
}
private static bool State21 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case 'u':
ctx.NextState = 22;
return true;
case '"':
case '\'':
case '/':
case '\\':
case 'b':
case 'f':
case 'n':
case 'r':
case 't':
ctx.L.string_buffer.Append (
ProcessEscChar (ctx.L.input_char));
ctx.NextState = ctx.StateStack;
return true;
default:
return false;
}
}
private static bool State22 (FsmContext ctx)
{
int counter = 0;
int mult = 4096;
ctx.L.unichar = 0;
while (ctx.L.GetChar ()) {
if (ctx.L.input_char >= '0' && ctx.L.input_char <= '9' ||
ctx.L.input_char >= 'A' && ctx.L.input_char <= 'F' ||
ctx.L.input_char >= 'a' && ctx.L.input_char <= 'f') {
ctx.L.unichar += HexValue (ctx.L.input_char) * mult;
counter++;
mult /= 16;
if (counter == 4) {
ctx.L.string_buffer.Append (
Convert.ToChar (ctx.L.unichar));
ctx.NextState = ctx.StateStack;
return true;
}
continue;
}
return false;
}
return true;
}
private static bool State23 (FsmContext ctx)
{
while (ctx.L.GetChar ()) {
switch (ctx.L.input_char) {
case '\'':
ctx.L.UngetChar ();
ctx.Return = true;
ctx.NextState = 24;
return true;
case '\\':
ctx.StateStack = 23;
ctx.NextState = 21;
return true;
default:
ctx.L.string_buffer.Append ((char) ctx.L.input_char);
continue;
}
}
return true;
}
private static bool State24 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case '\'':
ctx.L.input_char = '"';
ctx.Return = true;
ctx.NextState = 1;
return true;
default:
return false;
}
}
private static bool State25 (FsmContext ctx)
{
ctx.L.GetChar ();
switch (ctx.L.input_char) {
case '*':
ctx.NextState = 27;
return true;
case '/':
ctx.NextState = 26;
return true;
default:
return false;
}
}
private static bool State26 (FsmContext ctx)
{
while (ctx.L.GetChar ()) {
if (ctx.L.input_char == '\n') {
ctx.NextState = 1;
return true;
}
}
return true;
}
private static bool State27 (FsmContext ctx)
{
while (ctx.L.GetChar ()) {
if (ctx.L.input_char == '*') {
ctx.NextState = 28;
return true;
}
}
return true;
}
private static bool State28 (FsmContext ctx)
{
while (ctx.L.GetChar ()) {
if (ctx.L.input_char == '*')
continue;
if (ctx.L.input_char == '/') {
ctx.NextState = 1;
return true;
}
ctx.NextState = 27;
return true;
}
return true;
}
#endregion
private bool GetChar ()
{
if ((input_char = NextChar ()) != -1)
return true;
end_of_input = true;
return false;
}
private int NextChar ()
{
if (input_buffer != 0) {
int tmp = input_buffer;
input_buffer = 0;
return tmp;
}
return reader.Read ();
}
public bool NextToken ()
{
StateHandler handler;
fsm_context.Return = false;
while (true) {
handler = fsm_handler_table[state - 1];
if (! handler (fsm_context))
throw new JsonException (input_char);
if (end_of_input)
return false;
if (fsm_context.Return) {
string_value = string_buffer.ToString ();
string_buffer.Remove (0, string_buffer.Length);
token = fsm_return_table[state - 1];
if (token == (int) ParserToken.Char)
token = input_char;
state = fsm_context.NextState;
return true;
}
state = fsm_context.NextState;
}
}
private void UngetChar ()
{
input_buffer = input_char;
}
}
}
|