private static string ParseExpression(string code, string id, ParseMode mode, bool whenCondition, DekiScriptEnv env, DekiScriptRuntime runtime, Dictionary<string, string> channels, ref int i) {
StringBuilder result = new StringBuilder();
int nesting = 0;
for(; i < code.Length; ++i) {
int start;
switch(code[i]) {
case '"':
case '\'':
// process strings
start = i;
ScanString(code, code[i], ref i);
result.Append(code, start, i - start);
--i;
break;
case '/':
// check if / denotes the beginning of a comment, if so process it
start = i;
if(TryScanComment(code, ref i)) {
// NOTE: remove comments in when-condition
if(!whenCondition) {
result.Append(code, start, i - start);
result.Append("\n");
}
--i;
} else {
result.Append(code[i]);
}
break;
case '\\':
// backslash (\) always appends the next character
result.Append(code[i++]);
if(i < code.Length) {
result.Append(code[i]);
}
break;
case '(':
// increase nesting level
result.Append(code[i]);
++nesting;
break;
case '{':
// check if this is the beginning of a dekiscript block {{ }}
if(((i + 1) < code.Length) && (code[i + 1] == '{')) {
++i;
string value;
start = i;
if(TryParseDekiScriptExpression(code, env, runtime, ref i, out value)) {
result.Append(value);
} else {
++nesting;
result.Append('{');
result.Append(code, start, i - start);
--i;
}
} else {
++nesting;
result.Append(code[i]);
}
break;
case ')':
case '}':
// decrease nesting level and check if this is the end of the sougth expression
result.Append(code[i]);
--nesting;
// NOTE: only exit if
// 1) we don't have to read all of the code
// 2) there are no open parentheses or cruly braces
// 3) we don't on a complete statement or the current characteris a closing curly brace
if((mode != ParseMode.ALL) && (nesting <= 0) && ((mode != ParseMode.STATEMENT) || (code[i] == '}'))) {
// found the end of the expression
++i;
return result.ToString();
}
break;
case ';':
// check if the statement is the end of the sougth expression
result.Append(code[i]);
// NOTE: only exit if
// 1) we don't have to read all of the code
// 2) there are no open parentheses or cruly braces
// 3) we stop on a complete statement
if((nesting <= 0) && (mode == ParseMode.STATEMENT)) {
// found the end of the expression
++i;
return result.ToString();
}
break;
case '@':
// channel name
if(channels != null) {
++i;
start = i;
string channel;
string name;
if((i < code.Length) && ((code[i] == '"') || (code[i] == '\''))) {
// process: @"channel_name" or @'channel_name'
ScanString(code, code[i], ref i);
channel = code.Substring(start, i - start);
name = channel.Substring(1, channel.Length - 2).UnescapeString();
} else {
// process: @channel_magic_id
ScanId(code, ref i);
name = code.Substring(start, i - start);
if(!channels.TryGetValue(name, out channel)) {
channel = env.GetMagicId(name).ToString();
}
}
start = i;
ScanWhitespace(code, ref i);
if((i < code.Length) && (code[i] == '(')) {
// process: @channel ( ... )
string message = ParseExpression(code, id, ParseMode.EXPRESSION, false, env, runtime, channels, ref i);
message = message.Substring(1, message.Length - 2).Trim();
if(message.Length == 0) {
result.AppendFormat("Deki.publish({0})", channel);
} else {
result.AppendFormat("Deki.publish({0}, {1})", channel, message);
}
} else {
// channel is used for reading; add it to the channel set to read on activation
channels[name] = channel;
// convert channel name and add whitespace
result.AppendFormat("$channels[{0}]", name.QuoteString());
result.Append(code, start, i - start);
}
--i;
} else {
result.Append(code[i]);
}
break;
case '#':
// NOTE: don't process #id in the when-condition
// element name
if(!whenCondition && (channels != null)) {
++i;
start = i;
// process: #id
ScanId(code, ref i);
string name = code.Substring(start, i - start);
result.Append("$(\"#" + name + "\")");
--i;
} else {
result.Append(code[i]);
}
break;
default:
// NOTE: don't process when() in the when-condition
// check if this is the beginning of an identifier
if(!whenCondition && IsAlpha(code[i])) {
start = i;
ScanId(code, ref i);
int j = i;
ScanWhitespace(code, ref j);
// check if scanned identifier is the keyword 'when'
if(((i - start) == WHEN.Length) && (string.Compare(code, start, WHEN, 0, WHEN.Length, StringComparison.Ordinal) == 0) && (j < code.Length) && (code[j] == '(')) {
i = j;
Dictionary<string, string> subChannels = new Dictionary<string, string>();
// parse the condition of the 'when()' statement
string condition = ParseExpression(code, id, ParseMode.EXPRESSION, true, env, runtime, subChannels, ref i);
// parse the body of the 'when()' expression
string body = ParseExpression(code, id, ParseMode.STATEMENT, false, env, runtime, subChannels, ref i);
BuildWhenStatement(condition.Trim(), id, body.Trim(), result, env, subChannels);
} else {
result.Append(code, start, i - start);
}
--i;
} else {
result.Append(code[i]);
}
break;
}
}
return result.ToString();
}
