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package compiler
import (
"github.com/d5/tengo/compiler/ast"
)
func (c *Compiler) compileForStmt(stmt *ast.ForStmt) error {
c.symbolTable = c.symbolTable.Fork(true)
defer func() {
c.symbolTable = c.symbolTable.Parent(false)
}()
// init statement
if stmt.Init != nil {
if err := c.Compile(stmt.Init); err != nil {
return err
}
}
// pre-condition position
preCondPos := len(c.currentInstructions())
// condition expression
postCondPos := -1
if stmt.Cond != nil {
if err := c.Compile(stmt.Cond); err != nil {
return err
}
// condition jump position
postCondPos = c.emit(stmt, OpJumpFalsy, 0)
}
// enter loop
loop := c.enterLoop()
// body statement
if err := c.Compile(stmt.Body); err != nil {
c.leaveLoop()
return err
}
c.leaveLoop()
// post-body position
postBodyPos := len(c.currentInstructions())
// post statement
if stmt.Post != nil {
if err := c.Compile(stmt.Post); err != nil {
return err
}
}
// back to condition
c.emit(stmt, OpJump, preCondPos)
// post-statement position
postStmtPos := len(c.currentInstructions())
if postCondPos >= 0 {
c.changeOperand(postCondPos, postStmtPos)
}
// update all break/continue jump positions
for _, pos := range loop.Breaks {
c.changeOperand(pos, postStmtPos)
}
for _, pos := range loop.Continues {
c.changeOperand(pos, postBodyPos)
}
return nil
}
func (c *Compiler) compileForInStmt(stmt *ast.ForInStmt) error {
c.symbolTable = c.symbolTable.Fork(true)
defer func() {
c.symbolTable = c.symbolTable.Parent(false)
}()
// for-in statement is compiled like following:
//
// for :it := iterator(iterable); :it.next(); {
// k, v := :it.get() // DEFINE operator
//
// ... body ...
// }
//
// ":it" is a local variable but will be conflict with other user variables
// because character ":" is not allowed.
// init
// :it = iterator(iterable)
itSymbol := c.symbolTable.Define(":it")
if err := c.Compile(stmt.Iterable); err != nil {
return err
}
c.emit(stmt, OpIteratorInit)
if itSymbol.Scope == ScopeGlobal {
c.emit(stmt, OpSetGlobal, itSymbol.Index)
} else {
c.emit(stmt, OpDefineLocal, itSymbol.Index)
}
// pre-condition position
preCondPos := len(c.currentInstructions())
// condition
// :it.HasMore()
if itSymbol.Scope == ScopeGlobal {
c.emit(stmt, OpGetGlobal, itSymbol.Index)
} else {
c.emit(stmt, OpGetLocal, itSymbol.Index)
}
c.emit(stmt, OpIteratorNext)
// condition jump position
postCondPos := c.emit(stmt, OpJumpFalsy, 0)
// enter loop
loop := c.enterLoop()
// assign key variable
if stmt.Key.Name != "_" {
keySymbol := c.symbolTable.Define(stmt.Key.Name)
if itSymbol.Scope == ScopeGlobal {
c.emit(stmt, OpGetGlobal, itSymbol.Index)
} else {
c.emit(stmt, OpGetLocal, itSymbol.Index)
}
c.emit(stmt, OpIteratorKey)
if keySymbol.Scope == ScopeGlobal {
c.emit(stmt, OpSetGlobal, keySymbol.Index)
} else {
c.emit(stmt, OpDefineLocal, keySymbol.Index)
}
}
// assign value variable
if stmt.Value.Name != "_" {
valueSymbol := c.symbolTable.Define(stmt.Value.Name)
if itSymbol.Scope == ScopeGlobal {
c.emit(stmt, OpGetGlobal, itSymbol.Index)
} else {
c.emit(stmt, OpGetLocal, itSymbol.Index)
}
c.emit(stmt, OpIteratorValue)
if valueSymbol.Scope == ScopeGlobal {
c.emit(stmt, OpSetGlobal, valueSymbol.Index)
} else {
c.emit(stmt, OpDefineLocal, valueSymbol.Index)
}
}
// body statement
if err := c.Compile(stmt.Body); err != nil {
c.leaveLoop()
return err
}
c.leaveLoop()
// post-body position
postBodyPos := len(c.currentInstructions())
// back to condition
c.emit(stmt, OpJump, preCondPos)
// post-statement position
postStmtPos := len(c.currentInstructions())
c.changeOperand(postCondPos, postStmtPos)
// update all break/continue jump positions
for _, pos := range loop.Breaks {
c.changeOperand(pos, postStmtPos)
}
for _, pos := range loop.Continues {
c.changeOperand(pos, postBodyPos)
}
return nil
}
|
