11 // We have some function naming conventions.
14 // scanX takes buf and position, returns new position (and maybe a value)
15 // peekX takes *parser, returns bool or string
16 // consumeX takes *parser and maybe a required literal, maybe returns value
17 // also updates the parser position
20 // parseX takes *parser, returns AST node, updates parser position
27 func (p *parser) errorf(format string, args ...interface{}) {
28 panic(parserErr{buf: p.buf, offset: p.pos, format: format, args: args})
31 // parse is the main entry point to the parser
32 func parse(buf []byte) (contracts []*Contract, err error) {
34 if val := recover(); val != nil {
35 if e, ok := val.(parserErr); ok {
42 p := &parser{buf: buf}
43 contracts = parseContracts(p)
49 func parseContracts(p *parser) []*Contract {
50 var result []*Contract
51 for peekKeyword(p) == "contract" {
52 contract := parseContract(p)
53 result = append(result, contract)
58 // contract name(p1, p2: t1, p3: t2) locks value { ... }
59 func parseContract(p *parser) *Contract {
60 consumeKeyword(p, "contract")
61 name := consumeIdentifier(p)
62 params := parseParams(p)
63 // locks amount of asset
64 consumeKeyword(p, "locks")
66 value.Amount = consumeIdentifier(p)
67 consumeKeyword(p, "of")
68 value.Asset = consumeIdentifier(p)
70 clauses := parseClauses(p)
72 return &Contract{Name: name, Params: params, Clauses: clauses, Value: value}
75 // (p1, p2: t1, p3: t2)
76 func parseParams(p *parser) []*Param {
80 for !peekTok(p, ")") {
86 pt := parseParamsType(p)
87 params = append(params, pt...)
93 func parseClauses(p *parser) []*Clause {
95 for !peekTok(p, "}") {
97 clauses = append(clauses, c)
102 func parseParamsType(p *parser) []*Param {
103 firstName := consumeIdentifier(p)
104 params := []*Param{&Param{Name: firstName}}
105 for peekTok(p, ",") {
107 name := consumeIdentifier(p)
108 params = append(params, &Param{Name: name})
111 typ := consumeIdentifier(p)
112 for _, parm := range params {
113 if tdesc, ok := types[typ]; ok {
116 p.errorf("unknown type %s", typ)
122 func parseClause(p *parser) *Clause {
124 consumeKeyword(p, "clause")
125 c.Name = consumeIdentifier(p)
126 c.Params = parseParams(p)
128 c.statements = parseStatements(p)
133 func parseStatements(p *parser) []statement {
134 var statements []statement
135 for !peekTok(p, "}") {
136 s := parseStatement(p)
137 statements = append(statements, s)
142 func parseStatement(p *parser) statement {
143 switch peekKeyword(p) {
145 return parseIfStmt(p)
147 return parseDefineStmt(p)
149 return parseAssignStmt(p)
151 return parseVerifyStmt(p)
153 return parseLockStmt(p)
155 return parseUnlockStmt(p)
157 panic(parseErr(p.buf, p.pos, "unknown keyword \"%s\"", peekKeyword(p)))
160 func parseIfStmt(p *parser) *ifStatement {
161 consumeKeyword(p, "if")
162 condition := parseExpr(p)
163 body := &IfStatmentBody{}
165 body.trueBody = parseStatements(p)
167 if peekKeyword(p) == "else" {
168 consumeKeyword(p, "else")
170 body.falseBody = parseStatements(p)
173 return &ifStatement{condition: condition, body: body}
176 func parseDefineStmt(p *parser) *defineStatement {
177 defineStat := &defineStatement{}
178 consumeKeyword(p, "define")
180 param.Name = consumeIdentifier(p)
182 variableType := consumeIdentifier(p)
183 if tdesc, ok := types[variableType]; ok {
186 p.errorf("unknown type %s", variableType)
188 defineStat.variable = param
191 defineStat.expr = parseExpr(p)
196 func parseAssignStmt(p *parser) *assignStatement {
197 consumeKeyword(p, "assign")
198 varName := consumeIdentifier(p)
201 return &assignStatement{variable: &Param{Name: varName}, expr: expr}
204 func parseVerifyStmt(p *parser) *verifyStatement {
205 consumeKeyword(p, "verify")
207 return &verifyStatement{expr: expr}
210 func parseLockStmt(p *parser) *lockStatement {
211 consumeKeyword(p, "lock")
212 lockedAmount := parseExpr(p)
213 consumeKeyword(p, "of")
214 lockedAsset := parseExpr(p)
215 consumeKeyword(p, "with")
216 program := parseExpr(p)
217 return &lockStatement{lockedAmount: lockedAmount, lockedAsset: lockedAsset, program: program}
220 func parseUnlockStmt(p *parser) *unlockStatement {
221 consumeKeyword(p, "unlock")
222 unlockedAmount := parseExpr(p)
223 consumeKeyword(p, "of")
224 unlockedAsset := parseExpr(p)
225 return &unlockStatement{unlockedAmount: unlockedAmount, unlockedAsset: unlockedAsset}
228 func parseExpr(p *parser) expression {
229 // Uses the precedence-climbing algorithm
230 // <https://en.wikipedia.org/wiki/Operator-precedence_parser#Precedence_climbing_method>
231 expr := parseUnaryExpr(p)
232 expr2, pos := parseExprCont(p, expr, 0)
234 p.errorf("expected expression")
240 func parseUnaryExpr(p *parser) expression {
241 op, pos := scanUnaryOp(p.buf, p.pos)
246 expr := parseUnaryExpr(p)
247 return &unaryExpr{op: op, expr: expr}
250 func parseExprCont(p *parser, lhs expression, minPrecedence int) (expression, int) {
252 op, pos := scanBinaryOp(p.buf, p.pos)
253 if pos < 0 || op.precedence < minPrecedence {
258 rhs := parseUnaryExpr(p)
261 op2, pos2 := scanBinaryOp(p.buf, p.pos)
262 if pos2 < 0 || op2.precedence <= op.precedence {
265 rhs, p.pos = parseExprCont(p, rhs, op2.precedence)
267 return nil, -1 // or is this an error?
270 lhs = &binaryExpr{left: lhs, right: rhs, op: op}
275 func parseExpr2(p *parser) expression {
276 if expr, pos := scanLiteralExpr(p.buf, p.pos); pos >= 0 {
283 func parseExpr3(p *parser) expression {
287 return &callExpr{fn: e, args: args}
292 func parseExpr4(p *parser) expression {
300 var elts []expression
303 for !peekTok(p, "]") {
310 elts = append(elts, e)
313 return listExpr(elts)
315 name := consumeIdentifier(p)
319 func parseArgs(p *parser) []expression {
320 var exprs []expression
323 for !peekTok(p, ")") {
330 exprs = append(exprs, e)
338 func peekKeyword(p *parser) string {
339 name, _ := scanIdentifier(p.buf, p.pos)
343 func peekTok(p *parser, token string) bool {
344 pos := scanTok(p.buf, p.pos, token)
350 var keywords = []string{
351 "contract", "clause", "verify", "output", "return",
352 "locks", "requires", "of", "lock", "with", "unlock",
355 func consumeKeyword(p *parser, keyword string) {
356 pos := scanKeyword(p.buf, p.pos, keyword)
358 p.errorf("expected keyword %s", keyword)
363 func consumeIdentifier(p *parser) string {
364 name, pos := scanIdentifier(p.buf, p.pos)
366 p.errorf("expected identifier")
372 func consumeTok(p *parser, token string) {
373 pos := scanTok(p.buf, p.pos, token)
375 p.errorf("expected %s token", token)
382 func scanUnaryOp(buf []byte, offset int) (*unaryOp, int) {
383 // Maximum munch. Make sure "-3" scans as ("-3"), not ("-", "3").
384 if _, pos := scanIntLiteral(buf, offset); pos >= 0 {
387 for _, op := range unaryOps {
388 newOffset := scanTok(buf, offset, op.op)
390 return &op, newOffset
396 func scanBinaryOp(buf []byte, offset int) (*binaryOp, int) {
397 offset = skipWsAndComments(buf, offset)
402 for i, op := range binaryOps {
403 offset2 := scanTok(buf, offset, op.op)
405 if found == nil || len(op.op) > len(found.op) {
406 found = &binaryOps[i]
411 return found, newOffset
414 // TODO(bobg): boolean literals?
415 func scanLiteralExpr(buf []byte, offset int) (expression, int) {
416 offset = skipWsAndComments(buf, offset)
417 intliteral, newOffset := scanIntLiteral(buf, offset)
419 return intliteral, newOffset
421 strliteral, newOffset := scanStrLiteral(buf, offset)
423 return strliteral, newOffset
425 bytesliteral, newOffset := scanBytesLiteral(buf, offset) // 0x6c249a...
427 return bytesliteral, newOffset
432 func scanIdentifier(buf []byte, offset int) (string, int) {
433 offset = skipWsAndComments(buf, offset)
435 for ; i < len(buf) && isIDChar(buf[i], i == offset); i++ {
440 return string(buf[offset:i]), i
443 func scanTok(buf []byte, offset int, s string) int {
444 offset = skipWsAndComments(buf, offset)
446 if bytes.HasPrefix(buf[offset:], prefix) {
447 return offset + len(prefix)
452 func scanKeyword(buf []byte, offset int, keyword string) int {
453 id, newOffset := scanIdentifier(buf, offset)
463 func scanIntLiteral(buf []byte, offset int) (integerLiteral, int) {
464 offset = skipWsAndComments(buf, offset)
466 if offset < len(buf) && buf[offset] == '-' {
470 for ; i < len(buf) && unicode.IsDigit(rune(buf[i])); i++ {
471 // the literal is BytesLiteral when it starts with 0x/0X
472 if buf[i] == '0' && i < len(buf)-1 && (buf[i+1] == 'x' || buf[i+1] == 'X') {
477 n, err := strconv.ParseInt(string(buf[start:i]), 10, 64)
481 return integerLiteral(n), i
486 func scanStrLiteral(buf []byte, offset int) (bytesLiteral, int) {
487 offset = skipWsAndComments(buf, offset)
488 if offset >= len(buf) || buf[offset] != '\'' {
489 return bytesLiteral{}, -1
491 var byteBuf bytesLiteral
492 for i := offset + 1; i < len(buf); i++ {
494 return byteBuf, i + 1
496 if buf[i] == '\\' && i < len(buf)-1 {
497 if c, ok := scanEscape(buf[i+1]); ok {
498 byteBuf = append(byteBuf, c)
503 byteBuf = append(byteBuf, buf[i])
505 panic(parseErr(buf, offset, "unterminated string literal"))
508 func scanBytesLiteral(buf []byte, offset int) (bytesLiteral, int) {
509 offset = skipWsAndComments(buf, offset)
510 if offset+4 >= len(buf) {
513 if buf[offset] != '0' || (buf[offset+1] != 'x' && buf[offset+1] != 'X') {
516 if !isHexDigit(buf[offset+2]) || !isHexDigit(buf[offset+3]) {
520 for ; i < len(buf); i += 2 {
522 panic(parseErr(buf, offset, "odd number of digits in hex literal"))
524 if !isHexDigit(buf[i]) {
527 if !isHexDigit(buf[i+1]) {
528 panic(parseErr(buf, offset, "odd number of digits in hex literal"))
531 decoded := make([]byte, hex.DecodedLen(i-(offset+2)))
532 _, err := hex.Decode(decoded, buf[offset+2:i])
534 return bytesLiteral{}, -1
536 return bytesLiteral(decoded), i
539 func skipWsAndComments(buf []byte, offset int) int {
541 for ; offset < len(buf); offset++ {
548 if c == '/' && offset < len(buf)-1 && buf[offset+1] == '/' {
550 offset++ // skip two chars instead of one
551 } else if !unicode.IsSpace(rune(c)) {
559 func isHexDigit(b byte) bool {
560 return (b >= '0' && b <= '9') || (b >= 'a' && b <= 'f') || (b >= 'A' && b <= 'F')
563 func isIDChar(c byte, initial bool) bool {
564 if c >= 'a' && c <= 'z' {
567 if c >= 'A' && c <= 'Z' {
576 return unicode.IsDigit(rune(c))
579 type parserErr struct {
586 func parseErr(buf []byte, offset int, format string, args ...interface{}) error {
587 return parserErr{buf: buf, offset: offset, format: format, args: args}
590 func (p parserErr) Error() string {
591 // Lines start at 1, columns start at 0, like nature intended.
594 for i := 0; i < p.offset; i++ {
595 if p.buf[i] == '\n' {
602 args := []interface{}{line, col}
603 args = append(args, p.args...)
604 return fmt.Sprintf("line %d, col %d: "+p.format, args...)
607 func scanEscape(c byte) (byte, bool) {
610 case '\'', '"', '\\':