private static Expression CreateExpression(ITokenConsumeScope consumer)
{
using (var scope = consumer.Begin())
{
Expression left = null;
foreach (var fac in unaryFactories.Concat(operandFactories))
{
left = fac(scope);
if (left != null)
{
scope.Commit();
break;
}
}
if (left == null)
{
return null;
}
foreach (var func in binaryFactories)
{
var cmd = func(left, consumer);
if (cmd != null)
{
scope.Commit();
return cmd;
}
}
return left;
}
}
private LightCommand GenerateCommand(ITokenConsumeScope consumer)
{
Func<ITokenConsumeScope, LightCommand>[] factories = new Func<ITokenConsumeScope, LightCommand>[]
{
GenerateToggleCommand, GenerateOffCommand,
GenerateOnCommand
};
using (var scope = consumer.Begin())
{
foreach (var func in factories)
{
LightCommand cmd = func(consumer);
if (cmd != null)
{
scope.Commit();
return cmd;
}
}
}
return null;
}
private RouteInfo EatRoute(ITokenConsumeScope scope)
{
using (var inner = scope.Begin())
{
string from, to;
int distance;
if (
inner.EatLiteral(out from)
.EatNamedLiteral("to")
.EatLiteral(out to)
.Eat(TokenType.Equal)
.EatInt(out distance)
.Ok())
{
inner.Commit();
return new RouteInfo(from, to, distance);
}
else
{
return null;
}
}
}
private LightCommand GenerateToggleCommand(ITokenConsumeScope scope)
{
using (var local = scope.Begin())
{
int x1, y1, x2, y2;
if (
!local.EatNamedLiteral("toggle")
.EatInt(out x1)
.EatComma()
.EatInt(out y1)
.EatNamedLiteral("through")
.EatInt(out x2)
.EatComma()
.EatInt(out y2)
.Ok())
{
return null;
}
local.Commit();
return new LightCommand(new Rectangle<int>(new Point2D<int>(x1, y1), new Point2D<int>(x2, y2)), LightCommandType.Toggle);
}
}
public static VariableExpression CreateVariableExpression(ITokenConsumeScope scope)
{
using (var local = scope.Begin())
{
string variableName;
if (local.EatLiteral(out variableName).Ok())
{
local.Commit();
return new VariableExpression(variableName);
}
return null;
}
}
public Expression CreateExpressions(ITokenConsumeScope consumer)
{
return CreateExpression(consumer);
}
public static Expression CreateBinaryExpression(int bits, Expression left, ITokenConsumeScope scope)
{
using (var local = scope.Begin())
{
string literal;
if (left != null && local.EatLiteral(out literal).Ok())
{
var right = CreateExpression(local);
if (right == null)
{
return null;
}
switch (literal)
{
case "LSHIFT":
local.Commit();
return new LeftShiftExpression(bits, left, right);
case "AND":
local.Commit();
return new AndExpression(bits, left, right);
case "OR":
local.Commit();
return new OrOperation(bits, left, right);
case "RSHIFT":
local.Commit();
return new RightShiftExpression(bits, left, right);
}
}
return null;
}
}
public static Expression CreateNotExpression(int bits, ITokenConsumeScope scope)
{
using (var local = scope.Begin())
{
if (local.EatNamedLiteral("NOT").Ok())
{
var exp = CreateExpression(local);
if (exp != null)
{
local.Commit();
return new NotExpression(bits, exp);
}
}
return null;
}
}
public static AssignStatement CreateAssignExpression(ITokenConsumeScope scope)
{
using (var local = scope.Begin())
{
var left = CreateExpression(local);
if (left != null && local.Eat(TokenType.SingleArrowRight).Ok())
{
var right = CreateVariableExpression(local);
if (right != null)
{
local.Commit();
return new AssignStatement(left, right);
}
}
return null;
}
}
public static NumberExpression CreateNumberExpression(int bits, ITokenConsumeScope scope)
{
using (var local = scope.Begin())
{
int variableValue;
if (local.EatInt(out variableValue).Ok())
{
local.Commit();
return new NumberExpression(bits, variableValue);
}
return null;
}
}