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case.boo
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case.boo
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namespace TURBU.Meta
import System.Collections.Generic
import Boo.Lang.Compiler
import Boo.Lang.Compiler.Ast
macro caseOf(caseValue as Expression):
private struct CaseBlock:
[Property(Expr)]
_expr as Expression
[Property(Body)]
_body as Block
private static def MakeIf(name as string, data as CaseBlock) as IfStatement:
result = IfStatement(data.Expr.LexicalInfo)
if data.Expr isa ListLiteralExpression:
result.Condition = [| $(ReferenceExpression(name)) in $(data.Expr) |]
else: result.Condition = [| $(ReferenceExpression(name)) == $(data.Expr) |]
result.TrueBlock = data.Body
return result
macro case(args as Expression*):
if args.Count == 0:
Context.Errors.Add(CompilerError(case, 'Each case label must have at least one argument'))
return
caseList = caseOf['List'] as List[of CaseBlock]
if not caseList:
caseOf['List'] = caseList = List[of CaseBlock]()
expr as Expression
if args.Count == 1:
expr = args[0]
else:
ll = ListLiteralExpression()
expr = ll
ll.Items.AddRange(args)
caseList.Add(CaseBlock(Expr: expr, Body: case.Body))
macro default:
caseOf['default'] = default.Body
caseList = caseOf['List'] as List[of CaseBlock]
if caseList is null:
Context.Errors.Add(CompilerError(caseOf, 'At least one case must be specified'))
return
unless caseOf.Body.IsEmpty:
Context.Errors.Add(CompilerError(caseOf, 'Body must only contain case and default blocks'))
return
result = Block(caseOf.LexicalInfo)
temp = Context.GetUniqueName('caseVar')
result.Add([| $(ReferenceExpression(temp)) = $caseValue|])
tail = MakeIf(temp, caseList[0])
result.Add(tail)
caseList.RemoveAt(0)
for block in caseList:
newCase = MakeIf(temp, block)
tail.FalseBlock = Block((newCase))
tail = newCase
defaultCase = caseOf['default'] as Statement
if(defaultCase):
tail.FalseBlock = Block((defaultCase))
return result