func()

in resolve/resolve.go [629:797]

• 137 lines of code
• 45 McCabe index (conditional complexity)

func (r *resolver) expr(e syntax.Expr) {
	switch e := e.(type) {
	case *syntax.Ident:
		r.use(e)

	case *syntax.Literal:

	case *syntax.ListExpr:
		for _, x := range e.List {
			r.expr(x)
		}

	case *syntax.CondExpr:
		r.expr(e.Cond)
		r.expr(e.True)
		r.expr(e.False)

	case *syntax.IndexExpr:
		r.expr(e.X)
		r.expr(e.Y)

	case *syntax.DictEntry:
		r.expr(e.Key)
		r.expr(e.Value)

	case *syntax.SliceExpr:
		r.expr(e.X)
		if e.Lo != nil {
			r.expr(e.Lo)
		}
		if e.Hi != nil {
			r.expr(e.Hi)
		}
		if e.Step != nil {
			r.expr(e.Step)
		}

	case *syntax.Comprehension:
		// The 'in' operand of the first clause (always a ForClause)
		// is resolved in the outer block; consider: [x for x in x].
		clause := e.Clauses[0].(*syntax.ForClause)
		r.expr(clause.X)

		// A list/dict comprehension defines a new lexical block.
		// Locals defined within the block will be allotted
		// distinct slots in the locals array of the innermost
		// enclosing container (function/module) block.
		r.push(&block{comp: e})

		const isAugmented = false
		r.assign(clause.Vars, isAugmented)

		for _, clause := range e.Clauses[1:] {
			switch clause := clause.(type) {
			case *syntax.IfClause:
				r.expr(clause.Cond)
			case *syntax.ForClause:
				r.assign(clause.Vars, isAugmented)
				r.expr(clause.X)
			}
		}
		r.expr(e.Body) // body may be *DictEntry
		r.pop()

	case *syntax.TupleExpr:
		for _, x := range e.List {
			r.expr(x)
		}

	case *syntax.DictExpr:
		for _, entry := range e.List {
			entry := entry.(*syntax.DictEntry)
			r.expr(entry.Key)
			r.expr(entry.Value)
		}

	case *syntax.UnaryExpr:
		r.expr(e.X)

	case *syntax.BinaryExpr:
		r.expr(e.X)
		r.expr(e.Y)

	case *syntax.DotExpr:
		r.expr(e.X)
		// ignore e.Name

	case *syntax.CallExpr:
		r.expr(e.Fn)
		var seenVarargs, seenKwargs bool
		var seenName map[string]bool
		var n, p int
		for _, arg := range e.Args {
			pos, _ := arg.Span()
			if unop, ok := arg.(*syntax.UnaryExpr); ok && unop.Op == syntax.STARSTAR {
				// **kwargs
				if seenKwargs {
					r.errorf(pos, "multiple **kwargs not allowed")
				}
				seenKwargs = true
				r.expr(arg)
			} else if ok && unop.Op == syntax.STAR {
				// *args
				if seenKwargs {
					r.errorf(pos, "*args may not follow **kwargs")
				} else if seenVarargs {
					r.errorf(pos, "multiple *args not allowed")
				}
				seenVarargs = true
				r.expr(arg)
			} else if binop, ok := arg.(*syntax.BinaryExpr); ok && binop.Op == syntax.EQ {
				// k=v
				n++
				if seenKwargs {
					r.errorf(pos, "keyword argument may not follow **kwargs")
				} else if seenVarargs {
					r.errorf(pos, "keyword argument may not follow *args")
				}
				x := binop.X.(*syntax.Ident)
				if seenName[x.Name] {
					r.errorf(x.NamePos, "keyword argument %s repeated", x.Name)
				} else {
					if seenName == nil {
						seenName = make(map[string]bool)
					}
					seenName[x.Name] = true
				}
				r.expr(binop.Y)
			} else {
				// positional argument
				p++
				if seenVarargs {
					r.errorf(pos, "positional argument may not follow *args")
				} else if seenKwargs {
					r.errorf(pos, "positional argument may not follow **kwargs")
				} else if len(seenName) > 0 {
					r.errorf(pos, "positional argument may not follow named")
				}
				r.expr(arg)
			}
		}

		// Fail gracefully if compiler-imposed limit is exceeded.
		if p >= 256 {
			pos, _ := e.Span()
			r.errorf(pos, "%v positional arguments in call, limit is 255", p)
		}
		if n >= 256 {
			pos, _ := e.Span()
			r.errorf(pos, "%v keyword arguments in call, limit is 255", n)
		}

	case *syntax.LambdaExpr:
		fn := &Function{
			Name:   "lambda",
			Pos:    e.Lambda,
			Params: e.Params,
			Body:   []syntax.Stmt{&syntax.ReturnStmt{Result: e.Body}},
		}
		e.Function = fn
		r.function(fn, e.Lambda)

	case *syntax.ParenExpr:
		r.expr(e.X)

	default:
		log.Panicf("unexpected expr %T", e)
	}
}