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switch.go
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switch.go
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package yakast
import (
"fmt"
"strings"
yak "github.com/yaklang/yaklang/common/yak/antlr4yak/parser"
"github.com/yaklang/yaklang/common/yak/antlr4yak/yakvm"
uuid "github.com/satori/go.uuid"
)
type switchContext struct {
startCodeIndex int
switchBreakScopeCounter int
}
func (y *YakCompiler) enterSwitchContext(start int) {
y.switchDepthStack.Push(&switchContext{
startCodeIndex: start,
})
}
func (y *YakCompiler) peekSwitchContext() *switchContext {
raw, ok := y.switchDepthStack.Peek().(*switchContext)
if ok {
return raw
} else {
return nil
}
}
func (y *YakCompiler) exitSwitchContext(end int) {
start := y.peekSwitchStartIndex()
if start <= 0 {
return
}
for _, c := range y.codes[start:] {
if c.Opcode == yakvm.OpBreak && c.Unary <= 0 {
// 设置 for 开始到结尾的所有语句的 Break Code 的跳转值
c.Unary = end
}
}
y.switchDepthStack.Pop()
}
func (y *YakCompiler) _VisitSwitchStmt(raw yak.ISwitchStmtContext) interface{} {
if y == nil || raw == nil {
return nil
}
i, _ := raw.(*yak.SwitchStmtContext)
if i == nil {
return nil
}
recoverRange := y.SetRange(i.BaseParserRuleContext)
defer recoverRange()
y.writeString("switch ")
var (
defaultCodeIndex int
switchExprIsEmpty bool
)
recoverSymtbl := y.SwitchSymbolTableInNewScope("switch", uuid.NewV4().String())
defer recoverSymtbl()
startIndex := y.GetNextCodeIndex()
y.enterSwitchContext(startIndex)
symbolName := fmt.Sprintf("$switch:%v$", y.GetNextCodeIndex())
expressionResultID, err := y.currentSymtbl.NewSymbolWithReturn(symbolName)
if err != nil {
y.panicCompilerError(CreateSymbolError, symbolName)
}
// 将表达式的值放入符号中
if e := i.Expression(); e != nil {
y.VisitExpression(i.Expression())
y.pushListWithLen(1)
// 设置左值,这个左值是一个新建的符号!
y.pushLeftRef(expressionResultID)
y.pushListWithLen(1)
// 为右值创建一个符号,这个符号为 rightExpressionSymbol
y.pushOperator(yakvm.OpAssign)
y.writeString(" {")
} else {
//y.pushUndefined()
switchExprIsEmpty = true
y.writeString("{")
}
y.writeNewLine()
allcases := i.AllCase()
lenOfAllCases := len(allcases)
jmpToEnd := make([]*yakvm.Code, 0, lenOfAllCases)
jmpToNextCase := make([]*yakvm.Code, 0, lenOfAllCases)
jmpFallthrough := make([]*yakvm.Code, 0)
nextCaseIndexs := make([]int, 0, lenOfAllCases)
nextStmtIndexs := make([]int, 0, lenOfAllCases)
for index := range allcases {
recoverSymtbl = y.SwitchSymbolTableInNewScope("case", uuid.NewV4().String())
y.writeString("case ")
var jmpToStmt []*yakvm.Code
// 获取下个case的位置
caseIndex := y.GetNextCodeIndex()
nextCaseIndexs = append(nextCaseIndexs, caseIndex)
// if 判断
iExprs := i.ExpressionList(index)
if iExprs != nil {
exprs := iExprs.(*yak.ExpressionListContext)
lenOfExprs := len(exprs.AllExpression())
// 如果只有一个表达式,则直接用eq判断
if lenOfExprs == 1 {
y.VisitExpression(exprs.AllExpression()[0])
if !switchExprIsEmpty {
y.pushRef(expressionResultID)
y.pushOperator(yakvm.OpEq)
}
} else { // 如果多个表达式,要短路处理
for i, e := range exprs.AllExpression() {
y.VisitExpression(e)
if !switchExprIsEmpty {
y.pushRef(expressionResultID)
y.pushOperator(yakvm.OpEq)
}
jmpToStmt = append(jmpToStmt, y.pushJmpIfTrue())
if i < lenOfExprs-1 {
y.writeString(", ")
}
}
// 最后补一个false,用于下面的jmpToNextCase条件判断
y.pushBool(false)
}
}
y.writeString(":")
y.writeNewLine()
y.incIndent()
// 如果不相等,跳转到下个case
jmpToNextCase = append(jmpToNextCase, y.pushJmpIfFalse())
// 获取下个statementlist的位置
stmtIndex := y.GetNextCodeIndex()
nextStmtIndexs = append(nextStmtIndexs, stmtIndex)
// 设置条件短路
for _, jmp := range jmpToStmt {
jmp.Unary = stmtIndex
}
// 执行case中的语句,由于有fallthrough需要获取上下文,不能直接用VisitStatementList和VisitStatement
recoverFormatBufferFunc := y.switchFormatBuffer()
iStmts := i.StatementList(index)
if iStmts != nil {
stmts := iStmts.(*yak.StatementListContext)
allStatement := stmts.AllStatement()
lenOfAllStatement := len(allStatement)
for i, istmt := range allStatement {
if istmt == nil {
continue
}
stmt := istmt.(*yak.StatementContext)
// 忽略开头的empty
if i == 0 && stmt.Empty() != nil {
continue
}
y.writeIndent()
if s := stmt.FallthroughStmt(); s != nil {
if y.NowInSwitch() {
y.writeString("fallthrough")
y.writeEOS(stmt.Eos())
jmp := y.pushJmp()
// 暂时设置为index, 后面会设置为跳转到下一个statementlist的位置
jmp.Unary = index
jmpFallthrough = append(jmpFallthrough, jmp)
continue
}
y.panicCompilerError(fallthroughError)
} else {
}
newline := y.VisitStatement(istmt.(*yak.StatementContext))
if i < lenOfAllStatement-1 && newline {
y.writeNewLine()
}
}
}
buf := recoverFormatBufferFunc()
buf = strings.Trim(buf, "\n")
y.writeString(buf)
y.decIndent()
y.writeNewLine()
// 跳转到switch结尾
jmpToEnd = append(jmpToEnd, y.pushJmp())
recoverSymtbl()
}
// 访问default statementlist
if i.Default() != nil {
recoverSymtbl = y.SwitchSymbolTableInNewScope("default", uuid.NewV4().String())
y.writeString("default:")
y.writeNewLine()
y.incIndent()
defaultCodeIndex = y.GetNextCodeIndex()
recoverFormatBufferFunc := y.switchFormatBuffer()
stmts := i.StatementList(len(allcases)).(*yak.StatementListContext)
// y.VisitStatementList(stmts)
allStatement := stmts.AllStatement()
lenOfAllStatement := len(allStatement)
for i, istmt := range allStatement {
if istmt == nil {
continue
}
stmt := istmt.(*yak.StatementContext)
// 忽略开头的empty
if i == 0 && stmt.Empty() != nil {
continue
}
y.writeIndent()
newline := y.VisitStatement(istmt.(*yak.StatementContext))
if i < lenOfAllStatement-1 && newline {
y.writeNewLine()
}
}
buf := recoverFormatBufferFunc()
buf = strings.Trim(buf, "\n")
y.writeString(buf)
y.decIndent()
y.writeNewLine()
recoverSymtbl()
}
endCodewithScopeEnd := y.GetNextCodeIndex()
// 如果没有default,则跳转到switch结尾
if defaultCodeIndex == 0 {
defaultCodeIndex = endCodewithScopeEnd
}
endCode := y.GetNextCodeIndex()
// 设置fallthrough跳转到下个statementlist的位置
for _, jmp := range jmpFallthrough {
// 最后一个的fallthrough应该跳转到default
if jmp.Unary == lenOfAllCases-1 {
jmp.Unary = defaultCodeIndex
} else {
jmp.Unary = nextStmtIndexs[jmp.Unary+1]
}
}
// 设置跳转到下个case的位置
for index, jmp := range jmpToNextCase[:len(jmpToNextCase)-1] {
jmp.Unary = nextCaseIndexs[index+1]
}
// 设置最后一个case跳转到default
jmpToNextCase[len(jmpToNextCase)-1].Unary = defaultCodeIndex
// 设置跳转到switch结尾的位置
for _, jmp := range jmpToEnd {
jmp.Unary = endCodewithScopeEnd
}
// 设置break跳转到switch结尾的位置,不需要处理内部的scopeEnd,因为break自带了scopeEnd
// 因为switch创建时,breakScope的层数从0开始,因此break只会退出switch-scope内部的scope, 最后仍然需要一个switch-scope的scopeEnd。
// endCode一定是最后的ScopeEnd
y.exitSwitchContext(endCode)
y.writeString("}")
return nil
}