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|
package parser
import (
"fmt"
"go/ast"
goparser "go/parser"
"strings"
)
type funcType struct {
name string
defPrefix string
callPrefix string
argNames string
args string
}
func parseFuncDef(b []byte) (*funcType, error) {
defStr := string(b)
// extract func name
n := strings.Index(defStr, "(")
if n < 0 {
return nil, fmt.Errorf("cannot find '(' in function definition")
}
name := defStr[:n]
defStr = defStr[n+1:]
defPrefix := ""
callPrefix := ""
if len(name) == 0 {
// Either empty func name or valid method definition. Let's check.
// parse method receiver
n = strings.Index(defStr, ")")
if n < 0 {
return nil, fmt.Errorf("cannot find ')' in func")
}
recvStr := defStr[:n]
defStr = defStr[n+1:]
exprStr := fmt.Sprintf("func (%s)", recvStr)
expr, err := goparser.ParseExpr(exprStr)
if err != nil {
return nil, fmt.Errorf("invalid method definition: %s", err)
}
ft := expr.(*ast.FuncType)
if len(ft.Params.List) != 1 || len(ft.Params.List[0].Names) != 1 {
// method receiver must contain only one param
return nil, fmt.Errorf("missing func or method name")
}
recvName := ft.Params.List[0].Names[0].Name
defPrefix = fmt.Sprintf("(%s) ", recvStr)
callPrefix = recvName + "."
// extract method name
n = strings.Index(defStr, "(")
if n < 0 {
return nil, fmt.Errorf("missing func name")
}
name = string(stripLeadingSpace([]byte(defStr[:n])))
if len(name) == 0 {
return nil, fmt.Errorf("missing method name")
}
defStr = defStr[n+1:]
}
// validate and collect func args
if len(defStr) == 0 || defStr[len(defStr)-1] != ')' {
return nil, fmt.Errorf("missing ')' at the end of func")
}
args := defStr[:len(defStr)-1]
exprStr := fmt.Sprintf("func (%s)", args)
expr, err := goparser.ParseExpr(exprStr)
if err != nil {
return nil, fmt.Errorf("invalid func args: %s", err)
}
ft := expr.(*ast.FuncType)
if ft.Results != nil {
return nil, fmt.Errorf("func mustn't return any results")
}
// extract arg names
var tmp []string
for _, f := range ft.Params.List {
if len(f.Names) == 0 {
return nil, fmt.Errorf("func cannot contain untyped arguments")
}
for _, n := range f.Names {
if n == nil {
return nil, fmt.Errorf("func cannot contain untyped arguments")
}
if _, isVariadic := f.Type.(*ast.Ellipsis); isVariadic {
tmp = append(tmp, n.Name+"...")
} else {
tmp = append(tmp, n.Name)
}
}
}
argNames := strings.Join(tmp, ", ")
if len(args) > 0 {
args = ", " + args
}
if len(argNames) > 0 {
argNames = ", " + argNames
}
return &funcType{
name: name,
defPrefix: defPrefix,
callPrefix: callPrefix,
argNames: argNames,
args: args,
}, nil
}
func parseFuncCall(b []byte) (*funcType, error) {
exprStr := string(b)
expr, err := goparser.ParseExpr(exprStr)
if err != nil {
return nil, err
}
ce, ok := expr.(*ast.CallExpr)
if !ok {
return nil, fmt.Errorf("missing function call")
}
callPrefix, name, err := getCallName(ce)
if err != nil {
return nil, err
}
argNames := exprStr[ce.Lparen : ce.Rparen-1]
if len(argNames) > 0 {
argNames = ", " + argNames
}
return &funcType{
name: name,
callPrefix: callPrefix,
argNames: argNames,
}, nil
}
func (f *funcType) DefStream(dst string) string {
return fmt.Sprintf("%s%s%s(%s *qt%s.Writer%s)", f.defPrefix, f.prefixStream(), f.name, dst, mangleSuffix, f.args)
}
func (f *funcType) CallStream(dst string) string {
return fmt.Sprintf("%s%s%s(%s%s)", f.callPrefix, f.prefixStream(), f.name, dst, f.argNames)
}
func (f *funcType) DefWrite(dst string) string {
return fmt.Sprintf("%s%s%s(%s qtio%s.Writer%s)", f.defPrefix, f.prefixWrite(), f.name, dst, mangleSuffix, f.args)
}
func (f *funcType) CallWrite(dst string) string {
return fmt.Sprintf("%s%s%s(%s%s)", f.callPrefix, f.prefixWrite(), f.name, dst, f.argNames)
}
func (f *funcType) DefString() string {
args := f.args
if len(args) > 0 {
// skip the first ', '
args = args[2:]
}
return fmt.Sprintf("%s%s(%s) string", f.defPrefix, f.name, args)
}
func (f *funcType) prefixWrite() string {
s := "write"
if isUpper(f.name[0]) {
s = "Write"
}
return s
}
func (f *funcType) prefixStream() string {
s := "stream"
if isUpper(f.name[0]) {
s = "Stream"
}
return s
}
func getCallName(ce *ast.CallExpr) (string, string, error) {
callPrefix := ""
name := ""
expr := ce.Fun
for {
switch x := expr.(type) {
case *ast.Ident:
if len(callPrefix) == 0 && len(name) == 0 {
return "", x.Name, nil
}
callPrefix = x.Name + "." + callPrefix
return callPrefix, name, nil
case *ast.SelectorExpr:
if len(name) == 0 {
name = x.Sel.Name
} else {
callPrefix = x.Sel.Name + "." + callPrefix
}
expr = x.X
default:
return "", "", fmt.Errorf("unexpected function name")
}
}
}
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