go-zig-compiler/internal/main.go

package main

import (
	"flag"
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"os"
	"strings"

	"git.frop.prof/luke/go-zig-compiler/internal/zig"
)

var (
	outputFilepath *string = flag.String("o", "out.zig", "Zig output filename")
)

func init() {
	flag.Parse()
}

func main() {
	inputFilepaths := flag.Args()

	if len(inputFilepaths) > 1 {
		panic("Only support one file!")
	} else if len(inputFilepaths) < 1 {
		panic("Must supply one input file")
	}

	inputFilepath := inputFilepaths[0]

	fset := token.NewFileSet()

	f, err := parser.ParseFile(fset, inputFilepath, nil, parser.AllErrors)
	if err != nil {
		panic(err)
	}

	zigRoot, err := translateToZig(f)
	if err != nil {
		panic(err)
	}
	
	outputFile, err := os.Create(*outputFilepath)
	if err != nil {
		panic(err)
	}
	defer outputFile.Close()
	
	err = zig.Write(outputFile, zigRoot)
	if err != nil {
		panic(err)
	}
}

func translateToZig(f *ast.File) (*zig.Root, error) {
	// Create the root AST node
	root := &zig.Root{
		ContainerMembers: []*zig.ContainerMember{},
	}

	// Add the std import
	root.ContainerMembers = append(root.ContainerMembers, &zig.ContainerMember{
		Decl: zig.DeclareGlobalVar("std", 
			zig.Call(zig.Id("@import"), zig.StringLit("std")),
			zig.GlobalVarConst,
		),
	})

	// Find and translate the main function
	for _, decl := range f.Decls {
		if fn, ok := decl.(*ast.FuncDecl); ok && fn.Name.Name == "main" {
			mainFunc, err := translateMainFunction(fn)
			if err != nil {
				return nil, err
			}
			root.ContainerMembers = append(root.ContainerMembers, &zig.ContainerMember{
				Decl: mainFunc,
			})
		}
	}

	return root, nil
}

func translateMainFunction(fn *ast.FuncDecl) (*zig.FnDecl, error) {
	// Create the main function
	stmts := []zig.Stmt{}
	
	// Translate each statement in the function body
	for _, stmt := range fn.Body.List {
		zigStmt, err := translateStatement(stmt)
		if err != nil {
			return nil, err
		}
		if zigStmt != nil {
			stmts = append(stmts, zigStmt)
		}
	}
	
	return zig.DeclareFn(
		"main",
		zig.Id("void"),
		zig.NewBlock(stmts...),
		nil,
		zig.FnExport,
	), nil
}

func translateStatement(stmt ast.Stmt) (zig.Stmt, error) {
	switch s := stmt.(type) {
	case *ast.ExprStmt:
		// Handle expression statements (like function calls)
		expr, err := translateExpression(s.X)
		if err != nil {
			return nil, err
		}
		return zig.NewExprStmt(expr), nil
	default:
		return nil, fmt.Errorf("unsupported statement type: %T", stmt)
	}
}

func translateExpression(expr ast.Expr) (zig.Expr, error) {
	switch e := expr.(type) {
	case *ast.CallExpr:
		// Handle function calls
		if ident, ok := e.Fun.(*ast.Ident); ok && ident.Name == "print" {
			// Translate print() to std.debug.print()
			args := []zig.Expr{}
			
			// First argument is the format string
			if len(e.Args) > 0 {
				if lit, ok := e.Args[0].(*ast.BasicLit); ok && lit.Kind == token.STRING {
					// Remove quotes and use the string value
					args = append(args, zig.StringLit(strings.Trim(lit.Value, `"`)))
				} else {
					return nil, fmt.Errorf("print() requires a string literal argument")
				}
			}
			
			// Second argument is always .{} for now
			args = append(args, zig.InitList())
			
			return zig.Call(
				zig.FieldAccess(
					zig.FieldAccess(zig.Id("std"), "debug"),
					"print",
				),
				args...,
			), nil
		}
		return nil, fmt.Errorf("unsupported function call: %v", e.Fun)
	default:
		return nil, fmt.Errorf("unsupported expression type: %T", expr)
	}
}