func()

in resolve/resolve.go [799:896]

• 73 lines of code
• 24 McCabe index (conditional complexity)

func (r *resolver) function(function *Function, pos syntax.Position) {
	// Resolve defaults in enclosing environment.
	for _, param := range function.Params {
		if binary, ok := param.(*syntax.BinaryExpr); ok {
			r.expr(binary.Y)
		}
	}

	// Enter function block.
	b := &block{function: function}
	r.push(b)

	var seenOptional bool
	var star *syntax.UnaryExpr // * or *args param
	var starStar *syntax.Ident // **kwargs ident
	var numKwonlyParams int
	for _, param := range function.Params {
		switch param := param.(type) {
		case *syntax.Ident:
			// e.g. x
			if starStar != nil {
				r.errorf(param.NamePos, "required parameter may not follow **%s", starStar.Name)
			} else if star != nil {
				numKwonlyParams++
			} else if seenOptional {
				r.errorf(param.NamePos, "required parameter may not follow optional")
			}
			if r.bind(param) {
				r.errorf(param.NamePos, "duplicate parameter: %s", param.Name)
			}

		case *syntax.BinaryExpr:
			// e.g. y=dflt
			if starStar != nil {
				r.errorf(param.OpPos, "optional parameter may not follow **%s", starStar.Name)
			} else if star != nil {
				numKwonlyParams++
			}
			if id := param.X.(*syntax.Ident); r.bind(id) {
				r.errorf(param.OpPos, "duplicate parameter: %s", id.Name)
			}
			seenOptional = true

		case *syntax.UnaryExpr:
			// * or *args or **kwargs
			if param.Op == syntax.STAR {
				if starStar != nil {
					r.errorf(param.OpPos, "* parameter may not follow **%s", starStar.Name)
				} else if star != nil {
					r.errorf(param.OpPos, "multiple * parameters not allowed")
				} else {
					star = param
				}
			} else {
				if starStar != nil {
					r.errorf(param.OpPos, "multiple ** parameters not allowed")
				}
				starStar = param.X.(*syntax.Ident)
			}
		}
	}

	// Bind the *args and **kwargs parameters at the end,
	// so that regular parameters a/b/c are contiguous and
	// there is no hole for the "*":
	//   def f(a, b, *args, c=0, **kwargs)
	//   def f(a, b, *,     c=0, **kwargs)
	if star != nil {
		if id, _ := star.X.(*syntax.Ident); id != nil {
			// *args
			if r.bind(id) {
				r.errorf(id.NamePos, "duplicate parameter: %s", id.Name)
			}
			function.HasVarargs = true
		} else if numKwonlyParams == 0 {
			r.errorf(star.OpPos, "bare * must be followed by keyword-only parameters")
		}
	}
	if starStar != nil {
		if r.bind(starStar) {
			r.errorf(starStar.NamePos, "duplicate parameter: %s", starStar.Name)
		}
		function.HasKwargs = true
	}

	function.NumKwonlyParams = numKwonlyParams
	r.stmts(function.Body)

	// Resolve all uses of this function's local vars,
	// and keep just the remaining uses of free/global vars.
	b.resolveLocalUses()

	// Leave function block.
	r.pop()

	// References within the function body to globals are not
	// resolved until the end of the module.
}