shader: Accept an ast directly

This is a preparation to modify the AST before passign to Compile.

internal/shader/shader.go

@@ -17,7 +17,6 @@ package shader
 import (
 	"fmt"
 	"go/ast"
-	"go/parser"
 	"go/token"
 	"strconv"
 	"strings"
@@ -106,13 +105,7 @@ func (p *ParseError) Error() string {
 	return strings.Join(p.errs, "\n")
 }
 
-func Compile(src []byte, vertexEntry, fragmentEntry string) (*shaderir.Program, error) {
+func Compile(fs *token.FileSet, f *ast.File, vertexEntry, fragmentEntry string) (*shaderir.Program, error) {
-	fs := token.NewFileSet()
-	f, err := parser.ParseFile(fs, "", src, parser.AllErrors)
-	if err != nil {
-		return nil, err
-	}
-
 	s := &compileState{
 		fs:            fs,
 		vertexEntry:   vertexEntry,

shader.go

@@ -15,6 +15,9 @@
 package ebiten
 
 import (
+	"go/parser"
+	"go/token"
+
 	"github.com/hajimehoshi/ebiten/internal/buffered"
 	"github.com/hajimehoshi/ebiten/internal/shader"
 )
@@ -24,7 +27,13 @@ type Shader struct {
 }
 
 func NewShader(src []byte) (*Shader, error) {
-	s, err := shader.Compile(src, "Vertex", "Fragment")
+	fs := token.NewFileSet()
+	f, err := parser.ParseFile(fs, "", src, parser.AllErrors)
+	if err != nil {
+		return nil, err
+	}
+
+	s, err := shader.Compile(fs, f, "Vertex", "Fragment")
 	if err != nil {
 		return nil, err
 	}