refactor: mv gen into cmd folder

cmd/gen/symbol.go

@@ -0,0 +1,108 @@
+package main
+
+import (
+	"errors"
+	"strconv"
+	"strings"
+)
+
+var (
+	errIsConstReplace = errors.New("is const replace")
+	errNoSuchSymbol   = errors.New("no such sybmol")
+)
+
+type symbolTable map[string]*symbol
+
+func (st symbolTable) apply(t string) string {
+	for _, s := range st {
+		t = s.replace(t)
+	}
+	return t
+}
+
+func (st symbolTable) contains(name string) bool {
+	_, ok := st[name]
+	return ok
+}
+
+type symbolType uintptr
+
+const (
+	// symbolTypeConst fields
+	//
+	//   0: const eval
+	symbolTypeConst symbolType = iota
+	// symbolTypeFunc fields
+	//
+	//   0: _para1_name, _para2_name, ...
+	//   1: replaceable eval
+	symbolTypeFunc
+)
+
+type symbol struct {
+	stype  symbolType
+	name   string
+	fields []string
+}
+
+func newSymbolConst(name, val string) *symbol {
+	return &symbol{
+		stype:  symbolTypeConst,
+		name:   name,
+		fields: []string{val},
+	}
+}
+
+func newSymbolFunc(name, paras, evals string) *symbol {
+	return &symbol{
+		stype:  symbolTypeFunc,
+		name:   name,
+		fields: []string{paras, evals},
+	}
+}
+
+func (s *symbol) extract1stFunc(txt string) (args []string, a, b int, err error) {
+	if s.stype == symbolTypeConst {
+		return nil, 0, 0, errIsConstReplace
+	}
+	a = strings.Index(txt, s.name)
+	if a < 0 {
+		return nil, 0, 0, errNoSuchSymbol
+	}
+	str, off, err := getInsideRoundBrakets(txt[a:])
+	if err != nil {
+		return nil, 0, 0, err
+	}
+	args = strings.Split(str, ",")
+	for i, arg := range args {
+		args[i] = strings.TrimSpace(arg)
+	}
+	return args, a, a + off, nil
+}
+
+func (s *symbol) replace(txt string) string {
+	switch s.stype {
+	case symbolTypeConst:
+		return strings.ReplaceAll(txt, s.name, s.fields[0])
+	case symbolTypeFunc:
+		paras := strings.Split(s.fields[0], ",")
+		txts := []string{}
+		for {
+			args, a, b, err := s.extract1stFunc(txt)
+			if err == errNoSuchSymbol {
+				txts = append(txts, txt)
+				return strings.Join(txts, "")
+			}
+			if len(paras) != len(args) {
+				panic("args " + strings.Join(args, ", ") + " count " + strconv.Itoa(len(args)) + " is different from recorded " + s.fields[0])
+			}
+			n := len(txts)
+			txts = append(txts, []string{txt[:a], "/* ", txt[a:b], ") */(", s.fields[1]}...)
+			for i, p := range paras {
+				txts[n+4] = strings.ReplaceAll(txts[n+4], strings.TrimSpace(p), args[i])
+			}
+			txt = txt[b:]
+		}
+	}
+	panic("unsupported symbol type " + strconv.Itoa(int(s.stype)))
+}