/// Read expression from string, evaluate it and return the value
public object Eval(string expression)
{
if (expression == null)
{
return(null);
}
if (_exprCache == null)
{
_exprCache = new PrecompiledCache(128);
}
IOperation ex = _exprCache[expression];
if (ex == null)
{
using (var sr = new ParsingReader(new StringReader(expression)))
{
ex = new Parser(TokenSpecialCharacters).Parse(sr);
sr.SkipWhiteSpace();
sr.ReadAndThrowIfNot(-1);
_exprCache[expression] = ex;
}
}
if (ex == null)
{
return(null);
}
return(Eval(ex));
}
private IOperation parseVar()
{
Operations.OperationVariableAccess va = new Operations.OperationVariableAccess();
var cc = _reader.Peek();
bool blockMode = (cc == '{');
StringBuilder sb = new StringBuilder();
if (!blockMode)
{
while ((cc = _reader.Peek()) != -1)
{
var ch = (char)cc;
if (!char.IsLetterOrDigit(ch) && _parser._tokenSpecialCharacters.IndexOf(ch) == -1)
{
break;
}
sb.Append(ch);
_reader.Read();
}
va.AddName(sb.ToString());
return(new Operations.OperationExpression(new IOperation[] { va }));
}
_reader.Read(); // Read {
var v = _parser.ParseMulti(_reader);
_reader.SkipWhiteSpaceAndComments();
_reader.ReadAndThrowIfNot('}'); // eat }
return(v);
}
/// Evaluate string and return the result of the evaluation, casted to the type T
public T Eval <T>(string st)
{
using (var sr = new ParsingReader(new StringReader(st)))
{
var o = Eval <T>(sr);
sr.SkipWhiteSpaceAndComments();
sr.ReadAndThrowIfNot(-1);
return(o);
}
}
/// <summary>
/// Try to get variable value
/// </summary>
/// <param name="key">Variable name</param>
/// <param name="value">Where to store found variable value</param>
/// <returns>true if variable is set</returns>
public override bool TryGetValue(string key, out object value)
{
if (!IsCalculated(key))
{
return(base.TryGetValue(key, out value));
}
using (var sr = new ParsingReader(key))
{
sr.SkipWhiteSpace();
value = sr.ReadNumber();
if (value != null)
{
sr.SkipWhiteSpace();
sr.ReadAndThrowIfNot(-1);
return(true);
}
}
value = EvalMulti(key);
return(true);
}
/// <summary>
/// Try to get variable value
/// </summary>
/// <param name="key">Variable name</param>
/// <param name="value">Where to store found variable value</param>
/// <returns>true if variable is set</returns>
public override bool TryGetValue(string key, out object value)
{
if (!IsCalculated(key))
{
return(base.TryGetValue(key, out value));
}
using (var sr = new ParsingReader(key))
{
sr.SkipWhiteSpace();
value = sr.ReadNumber();
if (value != null)
{
sr.SkipWhiteSpace();
sr.ReadAndThrowIfNot(-1);
return(true);
}
}
if (!string.IsNullOrEmpty(key))
{
switch (key[0])
{
case '%':
EnvironmentVariableTarget target = getTarget(ref key);
value = Environment.GetEnvironmentVariable(key, target);
return(value != null);
case '~':
value = Find(key.Substring(1), true);
return(true);
}
}
value = EvalMulti(key);
return(true);
}
/// Read multi-expression (like ${a|b|=3+5}) from the string, evaluate it and return the value
public object EvalMulti(string multiExpression)
{
if (multiExpression == null)
{
return(null);
}
if (_exprCache == null)
{
_exprCache = new PrecompiledCache(128);
}
IOperation o = _exprCache[multiExpression];
if (o == null)
{
using (var sr = new ParsingReader(new StringReader(multiExpression)))
{
o = new Parser(TokenSpecialCharacters).ParseMulti(sr);
sr.SkipWhiteSpace();
sr.ReadAndThrowIfNot(-1);
_exprCache[multiExpression] = o;
}
}
return(Eval(o));
}
private object expandVars(TransformRules rules, string s)
{
string begin;
string end;
if ((rules & TransformRules.ExpandDual) == TransformRules.ExpandDual)
{
begin = "${{";
end = "}}";
}
else if ((rules & TransformRules.ExpandDualSquare) == TransformRules.ExpandDualSquare)
{
begin = "[[";
end = "]]";
}
else if ((rules & TransformRules.ExpandSquare) == TransformRules.ExpandSquare)
{
begin = "[";
end = "]";
}
else if ((rules & TransformRules.Expand) == TransformRules.Expand)
{
begin = "${";
end = "}";
}
else
{
return(s);
}
if (s.IndexOf(begin, StringComparison.Ordinal) != -1)
{
StringBuilder sbNew = new StringBuilder();
using (var sr = new ParsingReader(new StringReader(s)))
{
int ptr = 0;
bool first = true;
while (!sr.IsEOF)
{
char ch = (char)sr.Read();
if (ch != begin[ptr])
{
sbNew.Append(begin, 0, ptr);
sbNew.Append(ch);
ptr = 0;
first = false;
continue;
}
ptr++;
if (ptr < begin.Length)
{
continue;
}
if (sr.Peek() == '{' || sr.Peek() == '[')
{
sbNew.Append(begin);
ptr = 0;
first = false;
continue;
}
//
object sv = EvalMulti(sr);
sv = ((rules & TransformRules.ExpandTrimOnly) == TransformRules.ExpandTrimOnly)
? Utils.TransformStr(Utils.To <string>(sv), rules & TransformRules.TrimMask)
: sv;
sv = ((rules & TransformRules.ExpandReplaceOnly) == TransformRules.ExpandReplaceOnly)
? Utils.TransformStr(Utils.To <string>(sv), rules & TransformRules.ReplaceMask)
: sv;
// Now read the trailing stuff
sr.SkipWhiteSpace();
for (ptr = 0; ptr < end.Length; ++ptr)
{
sr.ReadAndThrowIfNot(end[ptr]);
}
if (sr.IsEOF && first)
{
return(sv);
}
ptr = 0;
first = false;
sbNew.Append(Utils.To <string>(sv));
}
for (int i = 0; i < ptr; ++i)
{
sbNew.Append(begin[i]);
}
}
return(sbNew.ToString());
}
return(s);
}
