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//
// MarkupExpressionParser.cs
//
// This code is partly salvaged from moonlight. Following licence apply.
//
//
// Author(s):
// Moonlight List (moonlight-list@lists.ximian.com)
// Stephane Delcroix (stephane@mi8.be)
//
// Copyright 2009 Novell, Inc.
// Copyright 2013 Xamarin, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.Text;
namespace Xamarin.Forms.Xaml
{
internal abstract class MarkupExpressionParser
{
public object ParseExpression(ref string expression, IServiceProvider serviceProvider)
{
if (serviceProvider == null)
throw new ArgumentNullException("serviceProvider");
if (expression.StartsWith("{}", StringComparison.Ordinal))
return expression.Substring(2);
if (expression[expression.Length - 1] != '}')
throw new Exception("Expression must end with '}'");
int len;
string match;
if (!MatchMarkup(out match, expression, out len))
return false;
expression = expression.Substring(len).TrimStart();
if (expression.Length == 0)
throw new Exception("Expression did not end in '}'");
var parser = Activator.CreateInstance(GetType()) as IExpressionParser;
return parser.Parse(match, ref expression, serviceProvider);
}
internal static bool MatchMarkup(out string match, string expression, out int end)
{
if (expression.Length < 2)
{
end = 1;
match = null;
return false;
}
if (expression[0] != '{')
{
end = 2;
match = null;
return false;
}
int i;
bool found = false;
for (i = 1; i < expression.Length; i++)
{
if (expression[i] == ' ')
continue;
found = true;
break;
}
if (!found)
{
end = 3;
match = null;
return false;
}
int c;
for (c = 0; c + i < expression.Length; c++)
{
if (expression[i + c] == ' ' || expression[i + c] == '}')
break;
}
if (i + c == expression.Length)
{
end = 6;
match = null;
return false;
}
end = i + c;
match = expression.Substring(i, c);
return true;
}
protected void HandleProperty(string prop, IServiceProvider serviceProvider, ref string remaining, bool isImplicit)
{
char next;
object value = null;
string str_value;
if (isImplicit)
{
SetPropertyValue(null, prop, null, serviceProvider);
return;
}
remaining = remaining.TrimStart();
if (remaining.StartsWith("{", StringComparison.Ordinal))
{
value = ParseExpression(ref remaining, serviceProvider);
remaining = remaining.TrimStart();
if (remaining.Length > 0 && remaining[0] == ',')
remaining = remaining.Substring(1);
str_value = value as string;
}
else
str_value = GetNextPiece(ref remaining, out next);
SetPropertyValue(prop, str_value, value, serviceProvider);
}
protected abstract void SetPropertyValue(string prop, string strValue, object value, IServiceProvider serviceProvider);
protected string GetNextPiece(ref string remaining, out char next)
{
bool inString = false;
int end = 0;
char stringTerminator = '\0';
remaining = remaining.TrimStart();
if (remaining.Length == 0)
{
next = Char.MaxValue;
return null;
}
var piece = new StringBuilder();
// If we're inside a quoted string we append all chars to our piece until we hit the ending quote.
while (end < remaining.Length &&
(inString || (remaining[end] != '}' && remaining[end] != ',' && remaining[end] != '=')))
{
if (inString)
{
if (remaining[end] == stringTerminator)
{
inString = false;
end ++;
break;
}
}
else
{
if (remaining[end] == '\'' || remaining[end] == '"')
{
inString = true;
stringTerminator = remaining[end];
end ++;
continue;
}
}
// If this is an escape char, consume it and append the next char to our piece.
if (remaining[end] == '\\')
{
end ++;
if (end == remaining.Length)
break;
}
piece.Append(remaining[end]);
end++;
}
if (inString && end == remaining.Length)
throw new Exception("Unterminated quoted string");
if (end == remaining.Length && !remaining.EndsWith("}", StringComparison.Ordinal))
throw new Exception("Expression did not end with '}'");
if (end == 0)
{
next = Char.MaxValue;
return null;
}
next = remaining[end];
remaining = remaining.Substring(end + 1);
// Whitespace is trimmed from the end of the piece before stripping
// quote chars from the start/end of the string.
while (piece.Length > 0 && char.IsWhiteSpace(piece[piece.Length - 1]))
piece.Length --;
if (piece.Length >= 2)
{
char first = piece[0];
char last = piece[piece.Length - 1];
if ((first == '\'' && last == '\'') || (first == '"' && last == '"'))
{
piece.Remove(piece.Length - 1, 1);
piece.Remove(0, 1);
}
}
return piece.ToString();
}
}
}
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