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82 lines
2.1 KiB
Go
82 lines
2.1 KiB
Go
package main
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import (
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"fmt"
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"os"
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"strings"
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)
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func main() {
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if len(os.Args) != 2 {
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fmt.Println("Usage: astgen <output_directory>")
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os.Exit(64)
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}
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d := os.Args[1]
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if _, err := os.Stat(d); os.IsNotExist(err) {
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fmt.Println("Directory does not exist")
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os.Exit(74)
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}
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fmt.Println("Generating AST classes in", d)
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defineAst(d, "Expr", []string{
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"Error : Value string",
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"Binary : Left Expr, Operator token.Token, Right Expr",
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"Grouping : Expression Expr",
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"Literal : Value any",
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"Unary : Operator token.Token, Right Expr",
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})
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}
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func defineAst(outputDir, baseName string, types []string) {
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path := outputDir + "/" + strings.ToLower(baseName) + ".go"
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file, err := os.Create(path)
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if err != nil {
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fmt.Println("Error creating file", path)
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os.Exit(74)
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}
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defer file.Close()
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file.WriteString("package parser\n\n")
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file.WriteString("import \"golox/token\"\n\n")
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defineVisitor(file, baseName, types)
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file.WriteString("type " + baseName + " interface {\n")
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file.WriteString(" Accept(visitor " + baseName + "Visitor[any]) any\n")
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file.WriteString("}\n\n")
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for _, t := range types {
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defineType(file, baseName, t)
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}
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}
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func defineVisitor(file *os.File, baseName string, types []string) {
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file.WriteString("type " + baseName + "Visitor[T any] interface {\n")
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for _, t := range types {
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typeName := strings.TrimSpace(t[:strings.Index(t, ":")-1])
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file.WriteString(" Visit" + typeName + baseName + "(" + strings.ToLower(typeName) + " *" + typeName + baseName + ") T\n")
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}
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file.WriteString("}\n\n")
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}
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func defineType(file *os.File, baseName, typeString string) {
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typeName := strings.TrimSpace(typeString[:strings.Index(typeString, ":")-1])
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fields := strings.TrimSpace(typeString[strings.Index(typeString, ":")+1:])
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file.WriteString("type " + typeName + baseName + " struct {\n")
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for _, field := range strings.Split(fields, ", ") {
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file.WriteString(" " + field + "\n")
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}
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file.WriteString("}\n\n")
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file.WriteString("func (t *" + typeName + baseName + ") Accept(visitor " + baseName + "Visitor[any]) any {\n")
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file.WriteString(" return visitor.Visit" + typeName + baseName + "(t)\n")
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file.WriteString("}\n\n")
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}
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