shader: Parse assignments

internal/shader/block.go

@@ -16,6 +16,7 @@ package shader
 
 import (
 	"fmt"
+	"go/ast"
 	"go/token"
 	"strings"
 )
@@ -35,13 +36,13 @@ func (b *block) dump(indent int) []string {
 
 	for _, v := range b.vars {
 		init := ""
-		if v.init != "" {
-			init = " = " + v.init
+		if v.init != nil {
+			init = " = " + dumpExpr(v.init)
 		}
 		lines = append(lines, fmt.Sprintf("%svar %s %s%s", idt, v.name, v.typ, init))
 	}
 	for _, c := range b.consts {
-		lines = append(lines, fmt.Sprintf("%sconst %s %s = %s", idt, c.name, c.typ, c.init))
+		lines = append(lines, fmt.Sprintf("%sconst %s %s = %s", idt, c.name, c.typ, dumpExpr(c.init)))
 	}
 	for _, f := range b.funcs {
 		var args []string
@@ -77,12 +78,13 @@ type stmtType int
 
 const (
 	stmtNone stmtType = iota
+	stmtAssign
 	stmtReturn
 )
 
 type stmt struct {
 	stmtType stmtType
-	exprs    []expr
+	exprs    []ast.Expr
 }
 
 func (s *stmt) dump(indent int) []string {
@@ -92,12 +94,14 @@ func (s *stmt) dump(indent int) []string {
 	switch s.stmtType {
 	case stmtNone:
 		lines = append(lines, "%s(none)", idt)
+	case stmtAssign:
+		lines = append(lines, fmt.Sprintf("%s%s = %s", idt, dumpExpr(s.exprs[0]), dumpExpr(s.exprs[1])))
 	case stmtReturn:
 		var expr string
 		if len(s.exprs) > 0 {
 			var strs []string
 			for _, e := range s.exprs {
-				strs = append(strs, e.dump())
+				strs = append(strs, dumpExpr(e))
 			}
 			expr = " " + strings.Join(strs, ", ")
 		}
@@ -109,25 +113,22 @@ func (s *stmt) dump(indent int) []string {
 	return lines
 }
 
-type exprType int
-
-const (
-	exprNone exprType = iota
-	exprIdent
-)
-
-type expr struct {
-	exprType exprType
-	value    string
-}
-
-func (e *expr) dump() string {
-	switch e.exprType {
-	case exprNone:
-		return "(none)"
-	case exprIdent:
-		return e.value
+func dumpExpr(e ast.Expr) string {
+	switch e := e.(type) {
+	case *ast.BasicLit:
+		return e.Value
+	case *ast.CompositeLit:
+		t := parseType(e.Type)
+		var vals []string
+		for _, e := range e.Elts {
+			vals = append(vals, dumpExpr(e))
+		}
+		return fmt.Sprintf("%s{%s}", t, strings.Join(vals, ", "))
+	case *ast.Ident:
+		return e.Name
+	case *ast.SelectorExpr:
+		return fmt.Sprintf("%s.%s", dumpExpr(e.X), dumpExpr(e.Sel))
 	default:
-		return fmt.Sprintf("(unkown expr: %d)", e.exprType)
+		return fmt.Sprintf("(unkown expr: %#v)", e)
 	}
 }

internal/shader/shader.go

@@ -35,13 +35,13 @@ var (
 type variable struct {
 	name string
 	typ  typ
-	init string
+	init ast.Expr
 }
 
 type constant struct {
 	name string
 	typ  typ
-	init string
+	init ast.Expr
 }
 
 type function struct {
@@ -194,9 +194,9 @@ func (sh *Shader) parseVaryingStruct(t *ast.TypeSpec) {
 				sh.addError(f.Pos(), fmt.Sprintf("position members must be one"))
 				continue
 			}
-			t, err := parseType(f.Type)
-			if err != nil {
-				sh.addError(f.Type.Pos(), err.Error())
+			t := parseType(f.Type)
+			if t == typNone {
+				sh.addError(f.Type.Pos(), fmt.Sprintf("unexpected type: %s", f.Type))
 				continue
 			}
 			if t != typVec4 {
@@ -209,9 +209,9 @@ func (sh *Shader) parseVaryingStruct(t *ast.TypeSpec) {
 			}
 			continue
 		}
-		t, err := parseType(f.Type)
-		if err != nil {
-			sh.addError(f.Type.Pos(), err.Error())
+		t := parseType(f.Type)
+		if t == typNone {
+			sh.addError(f.Type.Pos(), fmt.Sprintf("unexpected type: %s", f.Type))
 			continue
 		}
 		if !t.numeric() {
@@ -230,20 +230,24 @@ func (sh *Shader) parseVaryingStruct(t *ast.TypeSpec) {
 func (s *Shader) parseVariable(vs *ast.ValueSpec) []variable {
 	var t typ
 	if vs.Type != nil {
-		var err error
-		t, err = parseType(vs.Type)
-		if err != nil {
-			s.addError(vs.Type.Pos(), err.Error())
+		t = parseType(vs.Type)
+		if t == typNone {
+			s.addError(vs.Type.Pos(), fmt.Sprintf("unexpected type: %s", vs.Type))
 			return nil
 		}
 	}
 
 	var vars []variable
-	for _, n := range vs.Names {
+	for i, n := range vs.Names {
+		var init ast.Expr
+		if len(vs.Values) > 0 {
+			init = vs.Values[i]
+		}
 		name := n.Name
 		vars = append(vars, variable{
 			name: name,
 			typ:  t,
+			init: init,
 		})
 	}
 	return vars
@@ -252,32 +256,19 @@ func (s *Shader) parseVariable(vs *ast.ValueSpec) []variable {
 func (s *Shader) parseConstant(vs *ast.ValueSpec) []constant {
 	var t typ
 	if vs.Type != nil {
-		var err error
-		t, err = parseType(vs.Type)
-		if err != nil {
-			s.addError(vs.Type.Pos(), err.Error())
+		t = parseType(vs.Type)
+		if t == typNone {
+			s.addError(vs.Type.Pos(), fmt.Sprintf("unexpected type: %s", vs.Type))
 			return nil
 		}
 	}
 
 	var cs []constant
 	for i, n := range vs.Names {
-		v := vs.Values[i]
-		var init string
-		switch v := v.(type) {
-		case *ast.BasicLit:
-			if v.Kind != token.INT && v.Kind != token.FLOAT {
-				s.addError(v.Pos(), fmt.Sprintf("literal must be int or float but %s", v.Kind))
-				return cs
-			}
-			init = v.Value // TODO: This should be go/constant.Value
-		default:
-			// TODO: Parse the expression.
-		}
 		cs = append(cs, constant{
 			name: n.Name,
 			typ:  t,
-			init: init,
+			init: vs.Values[i],
 		})
 	}
 	return cs
@@ -295,9 +286,9 @@ func (sh *Shader) parseFunc(d *ast.FuncDecl) function {
 
 	var args []variable
 	for _, f := range d.Type.Params.List {
-		t, err := parseType(f.Type)
-		if err != nil {
-			sh.addError(f.Type.Pos(), err.Error())
+		t := parseType(f.Type)
+		if t == typNone {
+			sh.addError(f.Type.Pos(), fmt.Sprintf("unexpected type: %s", f.Type))
 			continue
 		}
 		for _, n := range f.Names {
@@ -310,9 +301,9 @@ func (sh *Shader) parseFunc(d *ast.FuncDecl) function {
 
 	var rets []variable
 	for _, f := range d.Type.Results.List {
-		t, err := parseType(f.Type)
-		if err != nil {
-			sh.addError(f.Type.Pos(), err.Error())
+		t := parseType(f.Type)
+		if t == typNone {
+			sh.addError(f.Type.Pos(), fmt.Sprintf("unexpected type: %s", f.Type))
 			continue
 		}
 		if len(f.Names) == 0 {
@@ -344,22 +335,35 @@ func (sh *Shader) parseBlock(b *ast.BlockStmt) *block {
 	for _, l := range b.List {
 		switch l := l.(type) {
 		case *ast.AssignStmt:
-			if l.Tok == token.DEFINE {
+			switch l.Tok {
+			case token.DEFINE:
 				for _, s := range l.Lhs {
 					ident := s.(*ast.Ident)
 					block.vars = append(block.vars, variable{
 						name: ident.Name,
 					})
 				}
-			} else {
-				// TODO
+				for i := range l.Rhs {
+					block.stmts = append(block.stmts, stmt{
+						stmtType: stmtAssign,
+						exprs:    []ast.Expr{l.Lhs[i], l.Rhs[i]},
+					})
+				}
+			case token.ASSIGN:
+				// TODO: What about the statement `a,b = b,a?`
+				for i := range l.Rhs {
+					block.stmts = append(block.stmts, stmt{
+						stmtType: stmtAssign,
+						exprs:    []ast.Expr{l.Lhs[i], l.Rhs[i]},
+					})
+				}
 			}
 		case *ast.DeclStmt:
 			sh.parseDecl(block, l.Decl)
 		case *ast.ReturnStmt:
-			var exprs []expr
+			var exprs []ast.Expr
 			for _, r := range l.Results {
-				exprs = append(exprs, sh.parseExpr(r))
+				exprs = append(exprs, r)
 			}
 			block.stmts = append(block.stmts, stmt{
 				stmtType: stmtReturn,
@@ -379,17 +383,6 @@ func (sh *Shader) parseBlock(b *ast.BlockStmt) *block {
 	return block
 }
 
-func (sh *Shader) parseExpr(e ast.Expr) expr {
-	switch e := e.(type) {
-	case *ast.Ident:
-		return expr{
-			exprType: exprIdent,
-			value:    e.Name,
-		}
-	}
-	return expr{}
-}
-
 // Dump dumps the shader state in an intermediate language.
 func (s *Shader) Dump() string {
 	var lines []string

internal/shader/shader_test.go

@@ -64,10 +64,12 @@ const C1 float = 1
 const C2 float = 2
 const C3 float = 3
 func F1(a vec2, b vec2) (_ vec4) {
-	var c0 vec2
-	var c1 (none)
-	var c2 (none)
+	var c0 vec2 = a
+	var c1 (none) = b
+	var c2 (none) = 1.0
 	var c3 (none)
+	c1.x = c2.x
+	c3 = vec4{c0, c1}
 	return c2
 }
 `,

internal/shader/type.go

@@ -35,30 +35,30 @@ const (
 	typSampler2d
 )
 
-func parseType(expr ast.Expr) (typ, error) {
+func parseType(expr ast.Expr) typ {
 	switch t := expr.(type) {
 	case *ast.Ident:
 		switch t.Name {
 		case "float":
-			return typFloat, nil
+			return typFloat
 		case "vec2":
-			return typVec2, nil
+			return typVec2
 		case "vec3":
-			return typVec3, nil
+			return typVec3
 		case "vec4":
-			return typVec4, nil
+			return typVec4
 		case "mat2":
-			return typMat2, nil
+			return typMat2
 		case "mat3":
-			return typMat3, nil
+			return typMat3
 		case "mat4":
-			return typMat4, nil
+			return typMat4
 		case "sampler2d":
-			return typSampler2d, nil
+			return typSampler2d
 		}
 		// TODO: Parse array types
 	}
-	return 0, fmt.Errorf("invalid type: %s", expr)
+	return typNone
 }
 
 func (t typ) String() string {