예제 #1
0
파일: const.go 프로젝트: DanB91/dcpu
// parseConstants finds constant definitions and references to them.
// It replaces the references with the nodes denoting the value of
// the respective constants.
func parseConstants(ast *parser.AST, list []parser.Node) (out []parser.Node, err error) {
	var instr *parser.Instruction
	var expr *parser.Expression
	var name *parser.Name
	var ok bool

	consts := make(map[string][]parser.Node)

	for i := 0; i < len(list); i++ {
		if instr, ok = list[i].(*parser.Instruction); !ok {
			continue
		}

		name = instr.Children()[0].(*parser.Name)
		if name.Data != "equ" {
			continue
		}

		expr = instr.Children()[1].(*parser.Expression)
		name = expr.Children()[0].(*parser.Name)

		if _, ok = consts[name.Data]; ok {
			return nil, NewBuildError(
				ast.Files[instr.File()], instr.Line(), instr.Col(),
				"Duplicate constant %q.", name.Data)
		}

		expr = instr.Children()[2].(*parser.Expression)
		consts[name.Data] = expr.Children()

		// Remove constant node from AST.
		copy(list[i:], list[i+1:])
		list = list[:len(list)-1]
		i--
	}

	for k, v := range consts {
		list = replaceConstantRef(list, k, v)
	}

	return list, nil
}
예제 #2
0
파일: funcs.go 프로젝트: DanB91/dcpu
// fixFunctionReturns finds 'return' instructions and replaces them
// with appropriate `set pc, $__<name>_epilog` versions.
func fixFunctionReturns(ast *parser.AST, f *parser.Function) {
	var instr *parser.Instruction
	var expr *parser.Expression
	var file, line, col int
	var code []parser.Node
	var ok bool

	name := f.Children()[0].(*parser.Name)
	exitLabel := "$__" + name.Data + "_epilog"
	list := f.Children()[1:]

	for i := range list {
		if instr, ok = list[i].(*parser.Instruction); !ok {
			continue
		}

		code = instr.Children()
		name = code[0].(*parser.Name)
		if name.Data != "return" {
			continue
		}

		file, line, col = instr.File(), instr.Line(), instr.Col()
		name.Data = "set"
		code = append(code, nil, nil)

		expr = parser.NewExpression(file, line, col)
		expr.SetChildren([]parser.Node{
			parser.NewName(file, line, col, "pc"),
		})
		code[1] = expr

		expr = parser.NewExpression(file, line, col)
		expr.SetChildren([]parser.Node{
			parser.NewName(file, line, col, exitLabel),
		})
		code[2] = expr

		instr.SetChildren(code)
	}
}