ebiten/internal/shader/stmt.go

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// Copyright 2020 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package shader
import (
"fmt"
"go/ast"
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gconstant "go/constant"
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"go/token"
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"strings"
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"github.com/hajimehoshi/ebiten/internal/shaderir"
)
func (cs *compileState) parseStmt(block *block, fname string, stmt ast.Stmt, inParams []variable) ([]shaderir.Stmt, bool) {
var stmts []shaderir.Stmt
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switch stmt := stmt.(type) {
case *ast.AssignStmt:
switch stmt.Tok {
case token.DEFINE:
if len(stmt.Lhs) != len(stmt.Rhs) && len(stmt.Rhs) != 1 {
cs.addError(stmt.Pos(), fmt.Sprintf("single-value context and multiple-value context cannot be mixed"))
return nil, false
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}
ss, ok := cs.assign(block, stmt.Pos(), stmt.Lhs, stmt.Rhs, true)
if !ok {
return nil, false
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}
stmts = append(stmts, ss...)
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case token.ASSIGN:
if len(stmt.Lhs) != len(stmt.Rhs) && len(stmt.Rhs) != 1 {
cs.addError(stmt.Pos(), fmt.Sprintf("single-value context and multiple-value context cannot be mixed"))
return nil, false
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}
ss, ok := cs.assign(block, stmt.Pos(), stmt.Lhs, stmt.Rhs, false)
if !ok {
return nil, false
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}
stmts = append(stmts, ss...)
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case token.ADD_ASSIGN, token.SUB_ASSIGN, token.MUL_ASSIGN, token.QUO_ASSIGN, token.REM_ASSIGN:
var op shaderir.Op
switch stmt.Tok {
case token.ADD_ASSIGN:
op = shaderir.Add
case token.SUB_ASSIGN:
op = shaderir.Sub
case token.MUL_ASSIGN:
op = shaderir.Mul
case token.QUO_ASSIGN:
op = shaderir.Div
case token.REM_ASSIGN:
op = shaderir.ModOp
}
rhs, _, ss, ok := cs.parseExpr(block, stmt.Rhs[0])
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if !ok {
return nil, false
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}
stmts = append(stmts, ss...)
lhs, ts, ss, ok := cs.parseExpr(block, stmt.Lhs[0])
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if !ok {
return nil, false
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}
stmts = append(stmts, ss...)
if rhs[0].Type == shaderir.NumberExpr {
if ts[0].Main == shaderir.Int {
if !canTruncateToInteger(rhs[0].Const) {
cs.addError(stmt.Pos(), fmt.Sprintf("constant %s truncated to integer", rhs[0].Const.String()))
return nil, false
}
rhs[0].ConstType = shaderir.ConstTypeInt
}
}
stmts = append(stmts, shaderir.Stmt{
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Type: shaderir.Assign,
Exprs: []shaderir.Expr{
lhs[0],
{
Type: shaderir.Binary,
Op: op,
Exprs: []shaderir.Expr{
lhs[0],
rhs[0],
},
},
},
})
default:
cs.addError(stmt.Pos(), fmt.Sprintf("unexpected token: %s", stmt.Tok))
}
case *ast.BlockStmt:
b, ok := cs.parseBlock(block, fname, stmt.List, inParams, nil)
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if !ok {
return nil, false
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}
stmts = append(stmts, shaderir.Stmt{
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Type: shaderir.BlockStmt,
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Blocks: []*shaderir.Block{
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b.ir,
},
})
case *ast.DeclStmt:
ss, ok := cs.parseDecl(block, stmt.Decl)
if !ok {
return nil, false
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}
stmts = append(stmts, ss...)
case *ast.ForStmt:
msg := "for-statement must follow this format: for (varname) := (constant); (varname) (op) (constant); (varname) (op) (constant) { ..."
if stmt.Init == nil {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if stmt.Cond == nil {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if stmt.Post == nil {
cs.addError(stmt.Pos(), msg)
return nil, false
}
// Create a new pseudo block for the initial statement, so that the counter variable belongs to the
// new pseudo block for each for-loop. Without this, the samely named counter variables in different
// for-loops confuses the parser.
pseudoBlock, ok := cs.parseBlock(block, fname, []ast.Stmt{stmt.Init}, inParams, nil)
if !ok {
return nil, false
}
ss := pseudoBlock.ir.Stmts
if len(ss) != 1 {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if ss[0].Type != shaderir.Assign {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if ss[0].Exprs[0].Type != shaderir.LocalVariable {
cs.addError(stmt.Pos(), msg)
return nil, false
}
varidx := ss[0].Exprs[0].Index
if ss[0].Exprs[1].Type != shaderir.NumberExpr {
cs.addError(stmt.Pos(), msg)
return nil, false
}
vartype := pseudoBlock.vars[0].typ
init := ss[0].Exprs[1].Const
exprs, ts, ss, ok := cs.parseExpr(pseudoBlock, stmt.Cond)
if !ok {
return nil, false
}
if len(exprs) != 1 {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if len(ts) != 1 || ts[0].Main != shaderir.Bool {
cs.addError(stmt.Pos(), "for-statement's condition must be bool")
return nil, false
}
if len(ss) != 0 {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if exprs[0].Type != shaderir.Binary {
cs.addError(stmt.Pos(), msg)
return nil, false
}
op := exprs[0].Op
if op != shaderir.LessThanOp && op != shaderir.LessThanEqualOp && op != shaderir.GreaterThanOp && op != shaderir.GreaterThanEqualOp && op != shaderir.EqualOp && op != shaderir.NotEqualOp {
cs.addError(stmt.Pos(), "for-statement's condition must have one of these operators: <, <=, >, >=, ==, !=")
return nil, false
}
if exprs[0].Exprs[0].Type != shaderir.LocalVariable {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if exprs[0].Exprs[0].Index != varidx {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if exprs[0].Exprs[1].Type != shaderir.NumberExpr {
cs.addError(stmt.Pos(), msg)
return nil, false
}
end := exprs[0].Exprs[1].Const
postSs, ok := cs.parseStmt(pseudoBlock, fname, stmt.Post, inParams)
if !ok {
return nil, false
}
if len(postSs) != 1 {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if postSs[0].Type != shaderir.Assign {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if postSs[0].Exprs[0].Type != shaderir.LocalVariable {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if postSs[0].Exprs[0].Index != varidx {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if postSs[0].Exprs[1].Type != shaderir.Binary {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if postSs[0].Exprs[1].Exprs[0].Type != shaderir.LocalVariable {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if postSs[0].Exprs[1].Exprs[0].Index != varidx {
cs.addError(stmt.Pos(), msg)
return nil, false
}
if postSs[0].Exprs[1].Exprs[1].Type != shaderir.NumberExpr {
cs.addError(stmt.Pos(), msg)
return nil, false
}
delta := postSs[0].Exprs[1].Exprs[1].Const
switch postSs[0].Exprs[1].Op {
case shaderir.Add:
case shaderir.Sub:
delta = gconstant.UnaryOp(token.SUB, delta, 0)
default:
cs.addError(stmt.Pos(), "for-statement's post statement must have one of these operators: +=, -=, ++, --")
return nil, false
}
b, ok := cs.parseBlock(pseudoBlock, fname, []ast.Stmt{stmt.Body}, inParams, nil)
if !ok {
return nil, false
}
bodyir := b.ir
for len(bodyir.Stmts) == 1 && bodyir.Stmts[0].Type == shaderir.BlockStmt {
bodyir = bodyir.Stmts[0].Blocks[0]
}
// As the pseudo block is not actually used, copy the variable part to the actual block.
// This must be done after parsing the for-loop is done, or the duplicated variables confuses the
// parsing.
v := pseudoBlock.vars[0]
v.forLoopCounter = true
block.vars = append(block.vars, v)
stmts = append(stmts, shaderir.Stmt{
Type: shaderir.For,
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Blocks: []*shaderir.Block{bodyir},
ForVarType: vartype,
ForVarIndex: varidx,
ForInit: init,
ForEnd: end,
ForOp: op,
ForDelta: delta,
})
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case *ast.IfStmt:
if stmt.Init != nil {
init := stmt.Init
stmt.Init = nil
b, ok := cs.parseBlock(block, fname, []ast.Stmt{init, stmt}, inParams, nil)
if !ok {
return nil, false
}
stmts = append(stmts, shaderir.Stmt{
Type: shaderir.BlockStmt,
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Blocks: []*shaderir.Block{b.ir},
})
return stmts, true
}
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exprs, ts, ss, ok := cs.parseExpr(block, stmt.Cond)
if !ok {
return nil, false
}
if len(ts) != 1 || ts[0].Main != shaderir.Bool {
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var tss []string
for _, t := range ts {
tss = append(tss, t.String())
}
cs.addError(stmt.Pos(), fmt.Sprintf("if-condition must be bool but: %s", strings.Join(tss, ", ")))
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return nil, false
}
stmts = append(stmts, ss...)
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var bs []*shaderir.Block
b, ok := cs.parseBlock(block, fname, stmt.Body.List, inParams, nil)
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if !ok {
return nil, false
}
bs = append(bs, b.ir)
if stmt.Else != nil {
switch s := stmt.Else.(type) {
case *ast.BlockStmt:
b, ok := cs.parseBlock(block, fname, s.List, inParams, nil)
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if !ok {
return nil, false
}
bs = append(bs, b.ir)
default:
b, ok := cs.parseBlock(block, fname, []ast.Stmt{s}, inParams, nil)
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if !ok {
return nil, false
}
bs = append(bs, b.ir)
}
}
stmts = append(stmts, shaderir.Stmt{
Type: shaderir.If,
Exprs: exprs,
Blocks: bs,
})
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case *ast.IncDecStmt:
exprs, _, ss, ok := cs.parseExpr(block, stmt.X)
if !ok {
return nil, false
}
stmts = append(stmts, ss...)
var op shaderir.Op
switch stmt.Tok {
case token.INC:
op = shaderir.Add
case token.DEC:
op = shaderir.Sub
}
stmts = append(stmts, shaderir.Stmt{
Type: shaderir.Assign,
Exprs: []shaderir.Expr{
exprs[0],
{
Type: shaderir.Binary,
Op: op,
Exprs: []shaderir.Expr{
exprs[0],
{
Type: shaderir.NumberExpr,
Const: gconstant.MakeInt64(1),
ConstType: shaderir.ConstTypeInt,
},
},
},
},
})
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case *ast.ReturnStmt:
for i, r := range stmt.Results {
exprs, _, ss, ok := cs.parseExpr(block, r)
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if !ok {
return nil, false
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}
stmts = append(stmts, ss...)
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if len(exprs) == 0 {
continue
}
if len(exprs) > 1 {
cs.addError(r.Pos(), "multiple-context with return is not implemented yet")
continue
}
stmts = append(stmts, shaderir.Stmt{
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Type: shaderir.Assign,
Exprs: []shaderir.Expr{
{
Type: shaderir.LocalVariable,
Index: len(inParams) + i,
},
exprs[0],
},
})
}
stmts = append(stmts, shaderir.Stmt{
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Type: shaderir.Return,
})
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case *ast.BranchStmt:
switch stmt.Tok {
case token.BREAK:
stmts = append(stmts, shaderir.Stmt{
Type: shaderir.Break,
})
case token.CONTINUE:
stmts = append(stmts, shaderir.Stmt{
Type: shaderir.Continue,
})
default:
cs.addError(stmt.Pos(), fmt.Sprintf("invalid token: %s", stmt.Tok))
return nil, false
}
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case *ast.ExprStmt:
exprs, _, ss, ok := cs.parseExpr(block, stmt.X)
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if !ok {
return nil, false
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}
stmts = append(stmts, ss...)
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for _, expr := range exprs {
if expr.Type != shaderir.Call {
continue
}
stmts = append(stmts, shaderir.Stmt{
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Type: shaderir.ExprStmt,
Exprs: []shaderir.Expr{expr},
})
}
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default:
cs.addError(stmt.Pos(), fmt.Sprintf("unexpected statement: %#v", stmt))
return nil, false
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}
return stmts, true
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}
func (cs *compileState) assign(block *block, pos token.Pos, lhs, rhs []ast.Expr, define bool) ([]shaderir.Stmt, bool) {
var stmts []shaderir.Stmt
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var rhsExprs []shaderir.Expr
var rhsTypes []shaderir.Type
for i, e := range lhs {
if len(lhs) == len(rhs) {
// Prase RHS first for the order of the statements.
r, origts, ss, ok := cs.parseExpr(block, rhs[i])
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if !ok {
return nil, false
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}
stmts = append(stmts, ss...)
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if define {
v := variable{
name: e.(*ast.Ident).Name,
}
ts, ok := cs.functionReturnTypes(block, rhs[i])
if !ok {
ts = origts
}
if len(ts) > 1 {
cs.addError(pos, fmt.Sprintf("single-value context and multiple-value context cannot be mixed"))
return nil, false
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}
if len(ts) == 1 {
v.typ = ts[0]
}
block.vars = append(block.vars, v)
}
if len(r) > 1 {
cs.addError(pos, fmt.Sprintf("single-value context and multiple-value context cannot be mixed"))
return nil, false
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}
l, _, ss, ok := cs.parseExpr(block, lhs[i])
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if !ok {
return nil, false
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}
stmts = append(stmts, ss...)
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if r[0].Type == shaderir.NumberExpr {
t, ok := block.findLocalVariableByIndex(l[0].Index)
if !ok {
cs.addError(pos, fmt.Sprintf("unexpected local variable index: %d", l[0].Index))
return nil, false
}
switch t.Main {
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case shaderir.Int:
r[0].ConstType = shaderir.ConstTypeInt
case shaderir.Float:
r[0].ConstType = shaderir.ConstTypeFloat
}
}
if len(lhs) == 1 {
stmts = append(stmts, shaderir.Stmt{
Type: shaderir.Assign,
Exprs: []shaderir.Expr{l[0], r[0]},
})
} else {
// For variable swapping, use temporary variables.
block.vars = append(block.vars, variable{
typ: origts[0],
})
idx := len(block.vars) - 1
stmts = append(stmts,
shaderir.Stmt{
Type: shaderir.Assign,
Exprs: []shaderir.Expr{
{
Type: shaderir.LocalVariable,
Index: idx,
},
r[0],
},
},
shaderir.Stmt{
Type: shaderir.Assign,
Exprs: []shaderir.Expr{
l[0],
{
Type: shaderir.LocalVariable,
Index: idx,
},
},
})
}
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} else {
if i == 0 {
var ss []shaderir.Stmt
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var ok bool
rhsExprs, rhsTypes, ss, ok = cs.parseExpr(block, rhs[0])
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if !ok {
return nil, false
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}
if len(rhsExprs) != len(lhs) {
cs.addError(pos, fmt.Sprintf("single-value context and multiple-value context cannot be mixed"))
}
stmts = append(stmts, ss...)
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}
if define {
v := variable{
name: e.(*ast.Ident).Name,
}
v.typ = rhsTypes[i]
block.vars = append(block.vars, v)
}
l, _, ss, ok := cs.parseExpr(block, lhs[i])
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if !ok {
return nil, false
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}
stmts = append(stmts, ss...)
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stmts = append(stmts, shaderir.Stmt{
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Type: shaderir.Assign,
Exprs: []shaderir.Expr{l[0], rhsExprs[i]},
})
}
}
return stmts, true
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}