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compiler: support for-range loops

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This commit is contained in:
Evgenii Stratonikov 2020-02-11 15:26:11 +03:00
parent bcff9faac4
commit 310f7449d7
2 changed files with 122 additions and 0 deletions
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39
pkg/compiler/codegen.go
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@ -660,6 +660,45 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
return nil
case *ast.RangeStmt:
// currently only simple for-range loops are supported
// for i := range ...
if n.Value != nil {
c.prog.Err = errors.New("range loops with value variable are not supported")
return nil
}
start := c.newLabel()
end := c.newLabel()
ast.Walk(c, n.X)
emit.Opcode(c.prog.BinWriter, opcode.ARRAYSIZE)
emit.Opcode(c.prog.BinWriter, opcode.PUSH0)
c.setLabel(start)
emit.Opcode(c.prog.BinWriter, opcode.OVER)
emit.Opcode(c.prog.BinWriter, opcode.OVER)
emit.Opcode(c.prog.BinWriter, opcode.LTE) // finish if len <= i
emit.Jmp(c.prog.BinWriter, opcode.JMPIF, int16(end))
if n.Key != nil {
emit.Opcode(c.prog.BinWriter, opcode.DUP)
pos := c.scope.loadLocal(n.Key.(*ast.Ident).Name)
c.emitStoreLocal(pos)
}
ast.Walk(c, n.Body)
emit.Opcode(c.prog.BinWriter, opcode.INC)
emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(start))
c.setLabel(end)
return nil
// We dont really care about assertions for the core logic.
// The only thing we need is to please the compiler type checking.
// For this to work properly, we only need to walk the expression