// 干净的源码没有多余的占位和注释, 解析过程就是选取干净的 Token 构成当前节点.
// 缩进, 占位, 注释,间隔符号, 分号, 换行只是被保存, 永远不会成为当前节点.
// 逗号, 分号, 换行用于产生 FFinal 标记, 并切换当前节点.
//
func Parse(src []byte, file *ast.File) (err error) {
var (
tabKind bool // 缩进风格
)
scan := scanner.New(src)
for err == nil && !scan.IsEOF() {
pos := scan.Pos()
code, ok := scan.Symbol()
if !ok {
err = errors.New("invalid UTF-8 encode")
break
}
tok := token.Lookup(code)
// 根节点, 只包含声明和占位, 非声明都转换为占位
if file.Active == file {
if !tok.As(token.Declare) {
// 占位扫描
var tmp string
for ok && tok != token.EOF && !tok.As(token.Declare) {
code += scan.Tail(true) + tmp
pos = scan.Pos()
tmp, ok = scan.Symbol()
tok = token.Lookup(tmp)
}
if !ok {
err = errors.New("invalid UTF-8 encode")
break
}
if err = file.Push(pos, token.PLACEHOLDER, code); err != nil {
break
}
code = tmp
}
err = file.Push(pos, tok, code)
continue
}
last := file.Last
// 脏 Token 全部由 File 解决, 并且不影响当前节点
//
switch tok {
case token.SPACES:
// 不支持 SPACES, TABS 混搭缩进
if last.Token() == token.INDENTATION ||
tabKind && last.Token() == token.NL {
err = errors.New("parser: bad indentation style for TABS + SPACES")
continue
}
if last.Token() == token.NL {
tok = token.INDENTATION
break
}
// 丢弃分隔空格
continue
case token.TABS:
if last.Token() == token.INDENTATION {
err = errors.New("parser: bad indentation style for SPACES + TABS")
continue
}
if last.Token() == token.NL {
tok = token.INDENTATION
tabKind = true
} else {
// TABS 尾注释
code += scan.Tail(false)
tok = token.COMMENT
}
case token.COMMENT:
err = file.Push(pos, tok, code+scan.Tail(false))
continue
case token.COMMENTS:
// 完整块注释
for !scan.IsEOF() {
tmp, _ := scan.Symbol()
code += tmp
tok = token.Lookup(tmp)
if tok == token.COMMENTS {
break
}
}
if tok != token.COMMENTS {
err = errors.New("parser: COMMENTS is incomplete")
} else {
err = file.Push(pos, tok, code+scan.Tail(false))
}
continue
case token.DOT: // MEMBER, SUGAR
case token.TRUE, token.FALSE:
tok = token.VALBOOL
case token.NAN, token.INFINITE:
tok = token.VALFLOAT
// case token.NULL:
case token.PLACEHOLDER:
// 识别语义, 只剩下字面值和标识符, 成员
if code == "\"" || code == "'" {
// 完整字符串
code += scan.EndString(code == "\"")
if scan.IsEOF() {
err = errors.New("parser: string is incomplete")
continue
}
tok = token.VALSTRING
break
}
// 整数, 浮点数, datetime
// ??? 缺少严格检查
if code[0] >= '0' && code[0] <= '9' {
tok = token.VALINTEGER
if code[0] == '0' && len(code) > 2 && (code[1] == 'x' || code[1] == 'b') {
} else {
for _, c := range code {
if c == '.' || c == 'e' {
tok = token.VALFLOAT
} else if c == 'T' || c == ':' || c == 'Z' {
tok = token.VALDATETIME
} else if (c < '0' || c > '9') && c != '+' && c != '-' && c != '_' {
tok = token.PLACEHOLDER
break
}
}
}
} else {
// 标识符, 成员
tok = token.IDENT
dot := 0
for _, c := range code {
if c == '.' {
dot++
continue
}
if c != '_' && !(c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9') {
tok = token.PLACEHOLDER
break
}
}
if dot != 0 && tok == token.IDENT {
if dot == 1 {
tok = token.MEMBER
} else {
tok = token.MEMBERS
}
}
}
}
if err == nil {
err = file.Push(pos, tok, code)
}
}
return
}
// Fast 快速解析, 转换, 合并 zxx 源码 src 中的 Token.
//
// 参数 rec 用于逐个接收解析到的 Token, 包括 EOF.
// 如果 rec 为 nil, 返回值 nodes 包含所有的 Token, 不包括 EOF.
//
// 缺陷:
//
// Fast 通过分析源码缩进判断顶层占位, 这可能对英文(非多字节)开始的顶层占位有影响.
// 常规的缩进或用 '//', '---' 开始英文顶层占位可以弥补缺陷.
//
func Fast(src []byte, cb func(scanner.Pos, token.Token, string) error) (nodes []Symbol, err error) {
var eml, indent string
var delay, tok, prev token.Token
if cb == nil {
nodes = make([]Symbol, 0, len(src)/10)
}
rec := func(pos scanner.Pos, tok token.Token, code string) (err error) {
// 合并空白行和占位为 PLACEHOLDER
switch tok {
case token.NL:
if delay == token.EOF {
delay = token.PLACEHOLDER
break
}
if prev == tok {
eml += code
if delay == token.EOF {
delay = token.NL
} else {
delay = token.PLACEHOLDER
}
return
}
if prev == token.INDENTATION {
eml += code
delay = token.PLACEHOLDER
return
}
break
case token.PLACEHOLDER, token.COMMENT:
if prev == token.INDENTATION {
eml += indent
indent = ""
}
eml += code
delay = token.PLACEHOLDER
return
case token.INDENTATION:
indent = code
return
}
if eml != "" {
if cb == nil {
nodes = append(nodes, Symbol{pos.Offset(-len(eml)), token.PLACEHOLDER, eml})
} else {
err = cb(pos.Offset(-len(eml)), token.PLACEHOLDER, eml)
if err != nil {
return
}
}
eml = ""
}
if prev == token.INDENTATION {
if cb == nil {
nodes = append(nodes, Symbol{pos.Offset(-len(indent)), token.INDENTATION, indent})
} else {
err = cb(pos.Offset(-len(indent)), token.INDENTATION, indent)
if err != nil {
return
}
}
indent = ""
}
if cb == nil {
nodes = append(nodes, Symbol{pos, tok, code})
} else {
err = cb(pos, tok, code)
}
return
}
tabKind := false
isTop := true
scan := scanner.New(src)
for err == nil {
pos := scan.Pos()
code, ok := scan.Symbol()
//fmt.Println(pos, code, token.Lookup(code))
if !ok {
err = errors.New("invalid UTF-8 encode")
return
}
prev = tok
tok = token.Lookup(code)
if tok == token.EOF {
if nodes == nil {
err = rec(pos, tok, code)
}
return
}
if isTop {
isTop = false
if !tok.As(token.Declare) {
var tmp string
posi := pos
for ok && tok != token.EOF && !tok.As(token.Declare) {
code += scan.Tail(true) + tmp
pos = scan.Pos()
tmp, ok = scan.Symbol()
tok = token.Lookup(tmp)
}
if !ok {
err = errors.New("invalid UTF-8 encode")
return
}
err = rec(posi, token.PLACEHOLDER, code)
code = tmp
}
if err == nil {
err = rec(pos, tok, code)
}
continue
}
switch tok {
case token.SPACES:
// 不支持 SPACES, TABS 混搭缩进
if prev == token.INDENTATION ||
tabKind && prev == token.NL {
err = errors.New("parser: bad indentation style for TABS + SPACES")
return
}
if prev == token.NL {
tok = token.INDENTATION
break
}
// 丢弃分隔空格
continue
case token.TABS:
if prev == token.INDENTATION {
err = errors.New("parser: bad indentation style for SPACES + TABS")
return
}
if prev == token.NL {
tok = token.INDENTATION
tabKind = true
} else {
// TABS 尾注释
code += scan.Tail(false)
tok = token.COMMENT
}
case token.COMMENT:
err = rec(pos, tok, code+scan.Tail(false))
continue
case token.COMMENTS:
// 完整块注释
for {
tmp, _ := scan.Symbol()
code += tmp
tok = token.Lookup(tmp)
if tok == token.COMMENTS || tok == token.EOF {
break
}
}
if tok != token.COMMENTS {
err = errors.New("parser: COMMENTS is incomplete")
return
}
err = rec(pos, tok, code+scan.Tail(false))
continue
case token.TRUE, token.FALSE:
tok = token.VALBOOL
case token.NAN, token.INFINITE:
tok = token.VALFLOAT
case token.PLACEHOLDER:
// 识别语义, 只剩下字面值和标识符, 成员
if code == `"` || code == `'` {
// 完整字符串
code += scan.EndString(code == `"`)
if code[0] != code[len(code)-1] {
err = errors.New("parser: string is incomplete")
return
}
tok = token.VALSTRING
break
}
// 整数, 浮点数, datetime
// ??? 缺少严格检查
if code[0] >= '0' && code[0] <= '9' {
tok = token.VALINTEGER
if code[0] == '0' && len(code) > 2 && (code[1] == 'x' || code[1] == 'b') {
} else {
for _, c := range code {
if c == '.' || c == 'e' {
tok = token.VALFLOAT
} else if c == 'T' || c == ':' || c == 'Z' {
tok = token.VALDATETIME
} else if (c < '0' || c > '9') && c != '+' && c != '-' && c != '_' {
tok = token.PLACEHOLDER
break
}
}
}
} else {
// 标识符, 成员
tok = token.IDENT
dot := 0
for _, c := range code {
if c == '.' {
dot++
continue
}
if c != '_' && !(c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9') {
tok = token.PLACEHOLDER
break
}
}
if dot != 0 && tok == token.IDENT {
if dot == 1 {
tok = token.MEMBER
} else {
tok = token.MEMBERS
}
}
}
}
err = rec(pos, tok, code)
}
return
}