int x ; 

{ 
	x = 10; //right
	int a = 10;
	a = x; //right 
}

a = 10; // wrong
int b = a; // wrong

grammar org.xtext.Cbb with org.eclipse.xtext.common.Terminals

generate cbb "http://www.xtext.org/Cbb"

Module:
	(statements+=Statement)*;
    
Statement:
	Variable |
	Block |
	IfStatement |
	WhileStatement |
	DoWhileStatement |
	ForStatement |
	SwitchStatement;

IfStatement:
	'if' '(' condition=Expression ')' 
	thenBlock=Block
	('else' 'if' '(' elseifConditions+=Expression ')'
	elseifthenBlocks+=Block)*
	(=>'else' elseBlock=Block)?;
	
WhileStatement:
	'while' '(' condition= Expression ')'
	whileBlock=Block;
	
DoWhileStatement:
	'do'
	doWhileBlock=Block
	'while' '(' condition=Expression ')'';';
	
ForStatement:
	'for''('((init=Variable)|(';'))(condition=Expression)?';'(increment=Expression)?')'
	forBlock=Block;

SwitchStatement:
	'switch' '('expr=Expression')'
	'{'
		('case' values+=integer_value ':'
			(caseStatements+=Statement)*
			('break'';')?
		)*
		('default'':'
			(defaultStatements+=Statement)*
		)?
	'}';

Block:
	{Block} '{' (blockStatements+=Statement)* '}';

Variable:
	VariableDeclaration | VariableAssignment;

VariableDeclaration:
	type=Type name=ID (op='=' expr=Expression)?';' |
	'const' type=Type name=ID op='=' expr=Expression';';

VariableAssignment: 
	assignee=[VariableDeclaration] op=assignment_operator expr=Expression';';

Expression returns Expression:
    BooleanExpression;
BooleanExpression returns Expression:
	Comparison
	({Expression.left=current} op=BooleanOperator right=Comparison)*;

Comparison returns Expression:
	Equal
	({Expression.left=current} op=ComparisonOperator right=Equal)*;

Equal returns Expression:
    Addition 
    ({Expression.left=current} op=EqualityOperator right=Addition)*;
    
Addition returns Expression:
    Multiplication
    ({Expression.left=current} op=AdditionOperator right=Multiplication)*;

Multiplication returns Expression:
    Bitwise 
    ({Expression.left=current} op=MultiplicationOperator right=Bitwise)*;

Bitwise returns Expression:
	Prefixed
	({Expression.left=current} op=BitwiseOperator right=Prefixed)*;

Prefixed returns Expression:
    {BooleanNegation} =>"!" expression=Atomic |
    {BitwiseNot} =>"~" expression=Atomic |
    Atomic;

Atomic returns Expression:
    lp='(' expr=Expression rp=')' |
    {IntegerLiteral} value=integer_value |
    {BooleanLiteral} value=boolean_value |
    {IntegerIncrementDecrement} (increment_decrement_operator ref=[VariableDeclaration]|ref=[VariableDeclaration] increment_decrement_operator) |
    {VariableReference} ref=[VariableDeclaration];

Type:
    {IntegerType} 'int' |
    {BooleanType} 'bool';

AdditionOperator:
	'+' | '-';
MultiplicationOperator:
	'*' | '/' | '%';
BitwiseOperator: 
	'|' | '&' | '^' | '>>' | '<<';
ComparisonOperator:
	'<' | '<=' | '>' | '>=';
EqualityOperator:
	'==' | '!=';
BooleanOperator: 
	'||' | '&&';

boolean_value:
	'true' | 'false';

assignment_operator:
	'=' | '+=' | '-=' | '*=' | '/=' | '%=' | '&=' | '|=' | '^=' | '<<='  | '>>=';
	
increment_decrement_operator:
	'++' | '--';

integer_value:
	'-'?INT+;

def dispatch IScope symbolsDefinedBefore(Block b, EObject o) {
		Scopes::scopeFor(b.blockStatements)
	}

getScope(EObject,EReference)

def IScope getVariableScope(EObject context) {
		if (context == null) {
			return IScope.NULLSCOPE
		}
		// get the block we are inside
		var block = EcoreUtil2.getContainerOfType(context, Block);
		if (block != null) {
			return Scopes.scopeFor(
				// var decls in that block
				block.blockStatements.filter(VariableDeclaration),
				// use name attribute
				QualifiedName.wrapper(SimpleAttributeResolver.NAME_RESOLVER),
				// the variable from outer blocks
				getVariableScope(block.eContainer)
			)
		} 
		// get the module we are inside
		var module = EcoreUtil2.getContainerOfType(context, Module)
		if (module != null) {
			return Scopes.scopeFor(module.statements.filter(VariableDeclaration))
		}
		//TODO handle possible other cases, handle order if relevant
		
		return IScope.NULLSCOPE
	}

class MyDslScopeProvider extends AbstractMyDslScopeProvider {
	
	override getScope(EObject context, EReference reference) {
		if (reference == MyDslPackage.Literals.VARIABLE_ASSIGNMENT__ASSIGNEE) {
			return getVariableScope(context)
		}
		super.getScope(context, reference)
	}
	
	def IScope getVariableScope(EObject context) {
		if (context == null) {
			return IScope.NULLSCOPE
		}
		// get the block we are inside
		var block = EcoreUtil2.getContainerOfType(context, Block);
		if (block != null) {
			return Scopes.scopeFor(
				// var decls in that block
				block.blockStatements.filter(VariableDeclaration),
				// use name attribute
				QualifiedName.wrapper(SimpleAttributeResolver.NAME_RESOLVER),
				// the variable from outer blocks
				getVariableScope(block.eContainer)
			)
		} 
		// get the module we are inside
		var module = EcoreUtil2.getContainerOfType(context, Module)
		if (module != null) {
			return Scopes.scopeFor(module.statements.filter(VariableDeclaration))
		}
		//TODO handle possible other cases, handle order if relevant
		
		return IScope.NULLSCOPE
	}

}

def IScope getVariableReferenceScope(EObject context) {
		if (context == null) {
			return IScope.NULLSCOPE
		}
		// get the block we are inside
		var block = EcoreUtil2.getContainerOfType(context, Block);
		if (block != null) {
			return Scopes.scopeFor(
				// var decls in that block
				block.blockStatements.filter(VariableDeclaration),
				// use name attribute
				QualifiedName.wrapper(SimpleAttributeResolver.NAME_RESOLVER),
				// the variable from outer blocks
				getVariableReferenceScope(block.eContainer)
			)
		} 
		// get the module we are inside
		var module = EcoreUtil2.getContainerOfType(context, Module)
		if (module != null) {
			return Scopes.scopeFor(module.statements.filter(VariableDeclaration))
		}
		//TODO handle possible other cases, handle order if relevant
		
		return IScope.NULLSCOPE
	}

int x = 0 ; 

{ 
	x = 10;
	int a = 10;
	a = x;
}

int a = 10; // Duplicate Statement 'a'
int b = a;

{
	int a = 10;
}

{
	int a = 10;
}

int a = 10;

class MyDslRuntimeModule extends AbstractMyDslRuntimeModule {
	
	override bindIQualifiedNameProvider() {
		MyQNP
	}
	
}