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parser.go
697 lines (646 loc) · 16.8 KB
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parser.go
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package lua
import (
"bufio"
"fmt"
"io"
"strings"
)
type parser struct {
scanner
function *function
activeVariables []int
pendingGotos, activeLabels []label
}
func (p *parser) checkCondition(c bool, message string) {
if !c {
p.syntaxError(message)
}
}
func (p *parser) checkName() string {
p.check(tkName)
s := p.s
p.next()
return s
}
func (p *parser) checkLimit(val, limit int, what string) {
if val > limit {
where := "main function"
if line := p.function.f.lineDefined; line != 0 {
where = fmt.Sprintf("function at line %d", line)
}
p.syntaxError(fmt.Sprintf("too many %s (limit is %d) in %s", what, limit, where))
}
}
func (p *parser) checkNext(t rune) {
p.check(t)
p.next()
}
func (p *parser) checkNameAsExpression() exprDesc { return p.function.EncodeString(p.checkName()) }
func (p *parser) singleVariable() exprDesc { return p.function.SingleVariable(p.checkName()) }
func (p *parser) leaveLevel() { p.l.nestedGoCallCount-- }
func (p *parser) enterLevel() {
p.l.nestedGoCallCount++
p.checkLimit(p.l.nestedGoCallCount, maxCallCount, "Go levels")
}
func (p *parser) expressionList() (e exprDesc, n int) {
for n, e = 1, p.expression(); p.testNext(','); n, e = n+1, p.expression() {
_ = p.function.ExpressionToNextRegister(e)
}
return
}
func (p *parser) field(tableRegister, a, h, pending int, e exprDesc) (int, int, int, exprDesc) {
freeRegisterCount := p.function.freeRegisterCount
hashField := func(k exprDesc) {
h++
p.checkNext('=')
p.function.FlushFieldToConstructor(tableRegister, freeRegisterCount, k, p.expression)
}
switch {
case p.t == tkName && p.lookAhead() == '=':
p.checkLimit(h, maxInt, "items in a constructor")
hashField(p.checkNameAsExpression())
case p.t == '[':
hashField(p.index())
default:
e = p.expression()
p.checkLimit(a, maxInt, "items in a constructor")
a++
pending++
}
return a, h, pending, e
}
func (p *parser) constructor() exprDesc {
pc, t := p.function.OpenConstructor()
line, a, h, pending := p.lineNumber, 0, 0, 0
var e exprDesc
if p.checkNext('{'); p.t != '}' {
for a, h, pending, e = p.field(t.info, a, h, pending, e); (p.testNext(',') || p.testNext(';')) && p.t != '}'; {
if e.kind != kindVoid {
pending = p.function.FlushToConstructor(t.info, pending, a, e)
e.kind = kindVoid
}
a, h, pending, e = p.field(t.info, a, h, pending, e)
}
}
p.checkMatch('}', '{', line)
p.function.CloseConstructor(pc, t.info, pending, a, h, e)
return t
}
func (p *parser) functionArguments(f exprDesc, line int) exprDesc {
var args exprDesc
switch p.t {
case '(':
p.next()
if p.t == ')' {
args.kind = kindVoid
} else {
args, _ = p.expressionList()
p.function.SetMultipleReturns(args)
}
p.checkMatch(')', '(', line)
case '{':
args = p.constructor()
case tkString:
args = p.function.EncodeString(p.s)
p.next()
default:
p.syntaxError("function arguments expected")
}
base, parameterCount := f.info, MultipleReturns
if !args.hasMultipleReturns() {
if args.kind != kindVoid {
args = p.function.ExpressionToNextRegister(args)
}
parameterCount = p.function.freeRegisterCount - (base + 1)
}
e := makeExpression(kindCall, p.function.EncodeABC(opCall, base, parameterCount+1, 2))
p.function.FixLine(line)
p.function.freeRegisterCount = base + 1 // call removed function and args & leaves (unless changed) one result
return e
}
func (p *parser) primaryExpression() (e exprDesc) {
switch p.t {
case '(':
line := p.lineNumber
p.next()
e = p.expression()
p.checkMatch(')', '(', line)
e = p.function.DischargeVariables(e)
case tkName:
e = p.singleVariable()
default:
p.syntaxError("unexpected symbol")
}
return
}
func (p *parser) suffixedExpression() exprDesc {
line := p.lineNumber
e := p.primaryExpression()
for {
switch p.t {
case '.':
e = p.fieldSelector(e)
case '[':
e = p.function.Indexed(p.function.ExpressionToAnyRegisterOrUpValue(e), p.index())
case ':':
p.next()
e = p.functionArguments(p.function.Self(e, p.checkNameAsExpression()), line)
case '(', tkString, '{':
e = p.functionArguments(p.function.ExpressionToNextRegister(e), line)
default:
return e
}
}
}
func (p *parser) simpleExpression() (e exprDesc) {
switch p.t {
case tkNumber:
e = makeExpression(kindNumber, 0)
e.value = p.n
case tkString:
e = p.function.EncodeString(p.s)
case tkNil:
e = makeExpression(kindNil, 0)
case tkTrue:
e = makeExpression(kindTrue, 0)
case tkFalse:
e = makeExpression(kindFalse, 0)
case tkDots:
p.checkCondition(p.function.f.isVarArg, "cannot use '...' outside a vararg function")
e = makeExpression(kindVarArg, p.function.EncodeABC(opVarArg, 0, 1, 0))
case '{':
e = p.constructor()
return
case tkFunction:
p.next()
e = p.body(false, p.lineNumber)
return
default:
e = p.suffixedExpression()
return
}
p.next()
return
}
func unaryOp(op rune) int {
switch op {
case tkNot:
return oprNot
case '-':
return oprMinus
case '#':
return oprLength
}
return oprNoUnary
}
func binaryOp(op rune) int {
switch op {
case '+':
return oprAdd
case '-':
return oprSub
case '*':
return oprMul
case '/':
return oprDiv
case '%':
return oprMod
case '^':
return oprPow
case tkConcat:
return oprConcat
case tkNE:
return oprNE
case tkEq:
return oprEq
case '<':
return oprLT
case tkLE:
return oprLE
case '>':
return oprGT
case tkGE:
return oprGE
case tkAnd:
return oprAnd
case tkOr:
return oprOr
}
return oprNoBinary
}
var priority []struct{ left, right int } = []struct{ left, right int }{
{6, 6}, {6, 6}, {7, 7}, {7, 7}, {7, 7}, // `+' `-' `*' `/' `%'
{10, 9}, {5, 4}, // ^, .. (right associative)
{3, 3}, {3, 3}, {3, 3}, // ==, <, <=
{3, 3}, {3, 3}, {3, 3}, // ~=, >, >=
{2, 2}, {1, 1}, // and, or
}
const unaryPriority = 8
func (p *parser) subExpression(limit int) (e exprDesc, op int) {
p.enterLevel()
if u := unaryOp(p.t); u != oprNoUnary {
line := p.lineNumber
p.next()
e, _ = p.subExpression(unaryPriority)
e = p.function.Prefix(u, e, line)
} else {
e = p.simpleExpression()
}
op = binaryOp(p.t)
for op != oprNoBinary && priority[op].left > limit {
line := p.lineNumber
p.next()
e = p.function.Infix(op, e)
e2, next := p.subExpression(priority[op].right)
e = p.function.Postfix(op, e, e2, line)
op = next
}
p.leaveLevel()
return
}
func (p *parser) expression() (e exprDesc) {
e, _ = p.subExpression(0)
return
}
func (p *parser) blockFollow(withUntil bool) bool {
switch p.t {
case tkElse, tkElseif, tkEnd, tkEOS:
return true
case tkUntil:
return withUntil
}
return false
}
func (p *parser) statementList() {
for !p.blockFollow(true) {
if p.t == tkReturn {
p.statement()
return
}
p.statement()
}
}
func (p *parser) fieldSelector(e exprDesc) exprDesc {
e = p.function.ExpressionToAnyRegisterOrUpValue(e)
p.next() // skip dot or colon
return p.function.Indexed(e, p.checkNameAsExpression())
}
func (p *parser) index() exprDesc {
p.next() // skip '['
e := p.function.ExpressionToValue(p.expression())
p.checkNext(']')
return e
}
func (p *parser) assignment(t *assignmentTarget, variableCount int) {
if p.checkCondition(t.isVariable(), "syntax error"); p.testNext(',') {
e := p.suffixedExpression()
if e.kind != kindIndexed {
p.function.CheckConflict(t, e)
}
p.checkLimit(variableCount+p.l.nestedGoCallCount, maxCallCount, "Go levels")
p.assignment(&assignmentTarget{previous: t, exprDesc: e}, variableCount+1)
} else {
p.checkNext('=')
if e, n := p.expressionList(); n != variableCount {
if p.function.AdjustAssignment(variableCount, n, e); n > variableCount {
p.function.freeRegisterCount -= n - variableCount // remove extra values
}
} else {
p.function.StoreVariable(t.exprDesc, p.function.SetReturn(e))
return // avoid default
}
}
p.function.StoreVariable(t.exprDesc, makeExpression(kindNonRelocatable, p.function.freeRegisterCount-1))
}
func (p *parser) forBody(base, line, n int, isNumeric bool) {
p.function.AdjustLocalVariables(3)
p.checkNext(tkDo)
prep := p.function.OpenForBody(base, n, isNumeric)
p.block()
p.function.CloseForBody(prep, base, line, n, isNumeric)
}
func (p *parser) forNumeric(name string, line int) {
expr := func() { p.assert(p.function.ExpressionToNextRegister(p.expression()).kind == kindNonRelocatable) }
base := p.function.freeRegisterCount
p.function.MakeLocalVariable("(for index)")
p.function.MakeLocalVariable("(for limit)")
p.function.MakeLocalVariable("(for step)")
p.function.MakeLocalVariable(name)
p.checkNext('=')
expr()
p.checkNext(',')
expr()
if p.testNext(',') {
expr()
} else {
p.function.EncodeConstant(p.function.freeRegisterCount, p.function.NumberConstant(1))
p.function.ReserveRegisters(1)
}
p.forBody(base, line, 1, true)
}
func (p *parser) forList(name string) {
n, base := 4, p.function.freeRegisterCount
p.function.MakeLocalVariable("(for generator)")
p.function.MakeLocalVariable("(for state)")
p.function.MakeLocalVariable("(for control)")
p.function.MakeLocalVariable(name)
for ; p.testNext(','); n++ {
p.function.MakeLocalVariable(p.checkName())
}
p.checkNext(tkIn)
line := p.lineNumber
e, c := p.expressionList()
p.function.AdjustAssignment(3, c, e)
p.function.CheckStack(3)
p.forBody(base, line, n-3, false)
}
func (p *parser) forStatement(line int) {
p.function.EnterBlock(true)
p.next()
switch name := p.checkName(); p.t {
case '=':
p.forNumeric(name, line)
case ',', tkIn:
p.forList(name)
default:
p.syntaxError("'=' or 'in' expected")
}
p.checkMatch(tkEnd, tkFor, line)
p.function.LeaveBlock()
}
func (p *parser) testThenBlock(escapes int) int {
var jumpFalse int
p.next()
e := p.expression()
p.checkNext(tkThen)
if p.t == tkGoto || p.t == tkBreak {
e = p.function.GoIfFalse(e)
p.function.EnterBlock(false)
p.gotoStatement(e.t)
p.skipEmptyStatements()
if p.blockFollow(false) {
p.function.LeaveBlock()
return escapes
}
jumpFalse = p.function.Jump()
} else {
e = p.function.GoIfTrue(e)
p.function.EnterBlock(false)
jumpFalse = e.f
}
p.statementList()
p.function.LeaveBlock()
if p.t == tkElse || p.t == tkElseif {
escapes = p.function.Concatenate(escapes, p.function.Jump())
}
p.function.PatchToHere(jumpFalse)
return escapes
}
func (p *parser) ifStatement(line int) {
escapes := p.testThenBlock(noJump)
for p.t == tkElseif {
escapes = p.testThenBlock(escapes)
}
if p.testNext(tkElse) {
p.block()
}
p.checkMatch(tkEnd, tkIf, line)
p.function.PatchToHere(escapes)
}
func (p *parser) block() {
p.function.EnterBlock(false)
p.statementList()
p.function.LeaveBlock()
}
func (p *parser) whileStatement(line int) {
p.next()
top, conditionExit := p.function.Label(), p.condition()
p.function.EnterBlock(true)
p.checkNext(tkDo)
p.block()
p.function.JumpTo(top)
p.checkMatch(tkEnd, tkWhile, line)
p.function.LeaveBlock()
p.function.PatchToHere(conditionExit) // false conditions finish the loop
}
func (p *parser) repeatStatement(line int) {
top := p.function.Label()
p.function.EnterBlock(true) // loop block
p.function.EnterBlock(false) // scope block
p.next()
p.statementList()
p.checkMatch(tkUntil, tkRepeat, line)
conditionExit := p.condition()
if p.function.block.hasUpValue {
p.function.PatchClose(conditionExit, p.function.block.activeVariableCount)
}
p.function.LeaveBlock() // finish scope
p.function.PatchList(conditionExit, top) // close loop
p.function.LeaveBlock() // finish loop
}
func (p *parser) condition() int {
e := p.expression()
if e.kind == kindNil {
e.kind = kindFalse
}
return p.function.GoIfTrue(e).f
}
func (p *parser) gotoStatement(pc int) {
if line := p.lineNumber; p.testNext(tkGoto) {
p.function.MakeGoto(p.checkName(), line, pc)
} else {
p.next()
p.function.MakeGoto("break", line, pc)
}
}
func (p *parser) skipEmptyStatements() {
for p.t == ';' || p.t == tkDoubleColon {
p.statement()
}
}
func (p *parser) labelStatement(label string, line int) {
p.function.CheckRepeatedLabel(label)
p.checkNext(tkDoubleColon)
l := p.function.MakeLabel(label, line)
p.skipEmptyStatements()
if p.blockFollow(false) {
p.activeLabels[l].activeVariableCount = p.function.block.activeVariableCount
}
p.function.FindGotos(l)
}
func (p *parser) parameterList() {
n, isVarArg := 0, false
if p.t != ')' {
for first := true; first || (!isVarArg && p.testNext(',')); first = false {
switch p.t {
case tkName:
p.function.MakeLocalVariable(p.checkName())
n++
case tkDots:
p.next()
isVarArg = true
default:
p.syntaxError("<name> or '...' expected")
}
}
}
// TODO the following lines belong in a *function method
p.function.f.isVarArg = isVarArg
p.function.AdjustLocalVariables(n)
p.function.f.parameterCount = p.function.activeVariableCount
p.function.ReserveRegisters(p.function.activeVariableCount)
}
func (p *parser) body(isMethod bool, line int) exprDesc {
p.function.OpenFunction(line)
p.checkNext('(')
if isMethod {
p.function.MakeLocalVariable("self")
p.function.AdjustLocalVariables(1)
}
p.parameterList()
p.checkNext(')')
p.statementList()
p.function.f.lastLineDefined = p.lineNumber
p.checkMatch(tkEnd, tkFunction, line)
return p.function.CloseFunction()
}
func (p *parser) functionName() (e exprDesc, isMethod bool) {
for e = p.singleVariable(); p.t == '.'; e = p.fieldSelector(e) {
}
if p.t == ':' {
e, isMethod = p.fieldSelector(e), true
}
return
}
func (p *parser) functionStatement(line int) {
p.next()
v, m := p.functionName()
p.function.StoreVariable(v, p.body(m, line))
p.function.FixLine(line)
}
func (p *parser) localFunction() {
p.function.MakeLocalVariable(p.checkName())
p.function.AdjustLocalVariables(1)
p.function.LocalVariable(p.body(false, p.lineNumber).info).startPC = pc(len(p.function.f.code))
}
func (p *parser) localStatement() {
v := 0
for first := true; first || p.testNext(','); v++ {
p.function.MakeLocalVariable(p.checkName())
first = false
}
if p.testNext('=') {
e, n := p.expressionList()
p.function.AdjustAssignment(v, n, e)
} else {
var e exprDesc
p.function.AdjustAssignment(v, 0, e)
}
p.function.AdjustLocalVariables(v)
}
func (p *parser) expressionStatement() {
if e := p.suffixedExpression(); p.t == '=' || p.t == ',' {
p.assignment(&assignmentTarget{exprDesc: e}, 1)
} else {
p.checkCondition(e.kind == kindCall, "syntax error")
p.function.Instruction(e).setC(1) // call statement uses no results
}
}
func (p *parser) returnStatement() {
if f := p.function; p.blockFollow(true) || p.t == ';' {
f.ReturnNone()
} else {
f.Return(p.expressionList())
}
p.testNext(';')
}
func (p *parser) statement() {
line := p.lineNumber
p.enterLevel()
switch p.t {
case ';':
p.next()
case tkIf:
p.ifStatement(line)
case tkWhile:
p.whileStatement(line)
case tkDo:
p.next()
p.block()
p.checkMatch(tkEnd, tkDo, line)
case tkFor:
p.forStatement(line)
case tkRepeat:
p.repeatStatement(line)
case tkFunction:
p.functionStatement(line)
case tkLocal:
p.next()
if p.testNext(tkFunction) {
p.localFunction()
} else {
p.localStatement()
}
case tkDoubleColon:
p.next()
p.labelStatement(p.checkName(), line)
case tkReturn:
p.next()
p.returnStatement()
case tkBreak, tkGoto:
p.gotoStatement(p.function.Jump())
default:
p.expressionStatement()
}
p.assert(p.function.f.maxStackSize >= p.function.freeRegisterCount && p.function.freeRegisterCount >= p.function.activeVariableCount)
p.function.freeRegisterCount = p.function.activeVariableCount
p.leaveLevel()
}
func (p *parser) mainFunction() {
p.function.OpenMainFunction()
p.next()
p.statementList()
p.check(tkEOS)
p.function = p.function.CloseMainFunction()
}
func (l *State) parse(r io.ByteReader, name string) *luaClosure {
p := &parser{scanner: scanner{r: r, lineNumber: 1, lastLine: 1, lookAheadToken: token{t: tkEOS}, l: l, source: name}}
f := &function{f: &prototype{source: name, maxStackSize: 2, isVarArg: true}, constantLookup: make(map[value]int), p: p, jumpPC: noJump}
p.function = f
p.mainFunction()
// TODO assertions about parser state
c := l.newLuaClosure(f.f)
l.push(c)
return c
}
func (l *State) checkMode(mode, x string) {
if mode != "" && !strings.Contains(mode, x[:1]) {
l.push(fmt.Sprintf("attempt to load a %s chunk (mode is '%s')", x, mode))
l.throw(SyntaxError)
}
}
func protectedParser(l *State, r io.Reader, name, chunkMode string) error {
l.nonYieldableCallCount++
err := l.protectedCall(func() {
var closure *luaClosure
b := bufio.NewReader(r)
if c, err := b.ReadByte(); err != nil {
l.checkMode(chunkMode, "text")
closure = l.parse(b, name)
} else if c == Signature[0] {
l.checkMode(chunkMode, "binary")
b.UnreadByte()
closure, _ = l.undump(b, name) // TODO handle err
} else {
l.checkMode(chunkMode, "text")
b.UnreadByte()
closure = l.parse(b, name)
}
l.assert(closure.upValueCount() == len(closure.prototype.upValues))
for i := range closure.upValues {
closure.upValues[i] = l.newUpValue()
}
}, l.top, l.errorFunction)
l.nonYieldableCallCount--
return err
}