aboutsummaryrefslogtreecommitdiff
path: root/vendor/gopkg.in/mgo.v2/internal/json/scanner.go
diff options
context:
space:
mode:
Diffstat (limited to 'vendor/gopkg.in/mgo.v2/internal/json/scanner.go')
-rw-r--r--vendor/gopkg.in/mgo.v2/internal/json/scanner.go697
1 files changed, 697 insertions, 0 deletions
diff --git a/vendor/gopkg.in/mgo.v2/internal/json/scanner.go b/vendor/gopkg.in/mgo.v2/internal/json/scanner.go
new file mode 100644
index 0000000..9708043
--- /dev/null
+++ b/vendor/gopkg.in/mgo.v2/internal/json/scanner.go
@@ -0,0 +1,697 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package json
+
+// JSON value parser state machine.
+// Just about at the limit of what is reasonable to write by hand.
+// Some parts are a bit tedious, but overall it nicely factors out the
+// otherwise common code from the multiple scanning functions
+// in this package (Compact, Indent, checkValid, nextValue, etc).
+//
+// This file starts with two simple examples using the scanner
+// before diving into the scanner itself.
+
+import "strconv"
+
+// checkValid verifies that data is valid JSON-encoded data.
+// scan is passed in for use by checkValid to avoid an allocation.
+func checkValid(data []byte, scan *scanner) error {
+ scan.reset()
+ for _, c := range data {
+ scan.bytes++
+ if scan.step(scan, c) == scanError {
+ return scan.err
+ }
+ }
+ if scan.eof() == scanError {
+ return scan.err
+ }
+ return nil
+}
+
+// nextValue splits data after the next whole JSON value,
+// returning that value and the bytes that follow it as separate slices.
+// scan is passed in for use by nextValue to avoid an allocation.
+func nextValue(data []byte, scan *scanner) (value, rest []byte, err error) {
+ scan.reset()
+ for i, c := range data {
+ v := scan.step(scan, c)
+ if v >= scanEndObject {
+ switch v {
+ // probe the scanner with a space to determine whether we will
+ // get scanEnd on the next character. Otherwise, if the next character
+ // is not a space, scanEndTop allocates a needless error.
+ case scanEndObject, scanEndArray, scanEndParams:
+ if scan.step(scan, ' ') == scanEnd {
+ return data[:i+1], data[i+1:], nil
+ }
+ case scanError:
+ return nil, nil, scan.err
+ case scanEnd:
+ return data[:i], data[i:], nil
+ }
+ }
+ }
+ if scan.eof() == scanError {
+ return nil, nil, scan.err
+ }
+ return data, nil, nil
+}
+
+// A SyntaxError is a description of a JSON syntax error.
+type SyntaxError struct {
+ msg string // description of error
+ Offset int64 // error occurred after reading Offset bytes
+}
+
+func (e *SyntaxError) Error() string { return e.msg }
+
+// A scanner is a JSON scanning state machine.
+// Callers call scan.reset() and then pass bytes in one at a time
+// by calling scan.step(&scan, c) for each byte.
+// The return value, referred to as an opcode, tells the
+// caller about significant parsing events like beginning
+// and ending literals, objects, and arrays, so that the
+// caller can follow along if it wishes.
+// The return value scanEnd indicates that a single top-level
+// JSON value has been completed, *before* the byte that
+// just got passed in. (The indication must be delayed in order
+// to recognize the end of numbers: is 123 a whole value or
+// the beginning of 12345e+6?).
+type scanner struct {
+ // The step is a func to be called to execute the next transition.
+ // Also tried using an integer constant and a single func
+ // with a switch, but using the func directly was 10% faster
+ // on a 64-bit Mac Mini, and it's nicer to read.
+ step func(*scanner, byte) int
+
+ // Reached end of top-level value.
+ endTop bool
+
+ // Stack of what we're in the middle of - array values, object keys, object values.
+ parseState []int
+
+ // Error that happened, if any.
+ err error
+
+ // 1-byte redo (see undo method)
+ redo bool
+ redoCode int
+ redoState func(*scanner, byte) int
+
+ // total bytes consumed, updated by decoder.Decode
+ bytes int64
+}
+
+// These values are returned by the state transition functions
+// assigned to scanner.state and the method scanner.eof.
+// They give details about the current state of the scan that
+// callers might be interested to know about.
+// It is okay to ignore the return value of any particular
+// call to scanner.state: if one call returns scanError,
+// every subsequent call will return scanError too.
+const (
+ // Continue.
+ scanContinue = iota // uninteresting byte
+ scanBeginLiteral // end implied by next result != scanContinue
+ scanBeginObject // begin object
+ scanObjectKey // just finished object key (string)
+ scanObjectValue // just finished non-last object value
+ scanEndObject // end object (implies scanObjectValue if possible)
+ scanBeginArray // begin array
+ scanArrayValue // just finished array value
+ scanEndArray // end array (implies scanArrayValue if possible)
+ scanBeginName // begin function call
+ scanParam // begin function argument
+ scanEndParams // end function call
+ scanSkipSpace // space byte; can skip; known to be last "continue" result
+
+ // Stop.
+ scanEnd // top-level value ended *before* this byte; known to be first "stop" result
+ scanError // hit an error, scanner.err.
+)
+
+// These values are stored in the parseState stack.
+// They give the current state of a composite value
+// being scanned. If the parser is inside a nested value
+// the parseState describes the nested state, outermost at entry 0.
+const (
+ parseObjectKey = iota // parsing object key (before colon)
+ parseObjectValue // parsing object value (after colon)
+ parseArrayValue // parsing array value
+ parseName // parsing unquoted name
+ parseParam // parsing function argument value
+)
+
+// reset prepares the scanner for use.
+// It must be called before calling s.step.
+func (s *scanner) reset() {
+ s.step = stateBeginValue
+ s.parseState = s.parseState[0:0]
+ s.err = nil
+ s.redo = false
+ s.endTop = false
+}
+
+// eof tells the scanner that the end of input has been reached.
+// It returns a scan status just as s.step does.
+func (s *scanner) eof() int {
+ if s.err != nil {
+ return scanError
+ }
+ if s.endTop {
+ return scanEnd
+ }
+ s.step(s, ' ')
+ if s.endTop {
+ return scanEnd
+ }
+ if s.err == nil {
+ s.err = &SyntaxError{"unexpected end of JSON input", s.bytes}
+ }
+ return scanError
+}
+
+// pushParseState pushes a new parse state p onto the parse stack.
+func (s *scanner) pushParseState(p int) {
+ s.parseState = append(s.parseState, p)
+}
+
+// popParseState pops a parse state (already obtained) off the stack
+// and updates s.step accordingly.
+func (s *scanner) popParseState() {
+ n := len(s.parseState) - 1
+ s.parseState = s.parseState[0:n]
+ s.redo = false
+ if n == 0 {
+ s.step = stateEndTop
+ s.endTop = true
+ } else {
+ s.step = stateEndValue
+ }
+}
+
+func isSpace(c byte) bool {
+ return c == ' ' || c == '\t' || c == '\r' || c == '\n'
+}
+
+// stateBeginValueOrEmpty is the state after reading `[`.
+func stateBeginValueOrEmpty(s *scanner, c byte) int {
+ if c <= ' ' && isSpace(c) {
+ return scanSkipSpace
+ }
+ if c == ']' {
+ return stateEndValue(s, c)
+ }
+ return stateBeginValue(s, c)
+}
+
+// stateBeginValue is the state at the beginning of the input.
+func stateBeginValue(s *scanner, c byte) int {
+ if c <= ' ' && isSpace(c) {
+ return scanSkipSpace
+ }
+ switch c {
+ case '{':
+ s.step = stateBeginStringOrEmpty
+ s.pushParseState(parseObjectKey)
+ return scanBeginObject
+ case '[':
+ s.step = stateBeginValueOrEmpty
+ s.pushParseState(parseArrayValue)
+ return scanBeginArray
+ case '"':
+ s.step = stateInString
+ return scanBeginLiteral
+ case '-':
+ s.step = stateNeg
+ return scanBeginLiteral
+ case '0': // beginning of 0.123
+ s.step = state0
+ return scanBeginLiteral
+ case 'n':
+ s.step = stateNew0
+ return scanBeginName
+ }
+ if '1' <= c && c <= '9' { // beginning of 1234.5
+ s.step = state1
+ return scanBeginLiteral
+ }
+ if isName(c) {
+ s.step = stateName
+ return scanBeginName
+ }
+ return s.error(c, "looking for beginning of value")
+}
+
+func isName(c byte) bool {
+ return c == '$' || c == '_' || 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || '0' <= c && c <= '9'
+}
+
+// stateBeginStringOrEmpty is the state after reading `{`.
+func stateBeginStringOrEmpty(s *scanner, c byte) int {
+ if c <= ' ' && isSpace(c) {
+ return scanSkipSpace
+ }
+ if c == '}' {
+ n := len(s.parseState)
+ s.parseState[n-1] = parseObjectValue
+ return stateEndValue(s, c)
+ }
+ return stateBeginString(s, c)
+}
+
+// stateBeginString is the state after reading `{"key": value,`.
+func stateBeginString(s *scanner, c byte) int {
+ if c <= ' ' && isSpace(c) {
+ return scanSkipSpace
+ }
+ if c == '"' {
+ s.step = stateInString
+ return scanBeginLiteral
+ }
+ if isName(c) {
+ s.step = stateName
+ return scanBeginName
+ }
+ return s.error(c, "looking for beginning of object key string")
+}
+
+// stateEndValue is the state after completing a value,
+// such as after reading `{}` or `true` or `["x"`.
+func stateEndValue(s *scanner, c byte) int {
+ n := len(s.parseState)
+ if n == 0 {
+ // Completed top-level before the current byte.
+ s.step = stateEndTop
+ s.endTop = true
+ return stateEndTop(s, c)
+ }
+ if c <= ' ' && isSpace(c) {
+ s.step = stateEndValue
+ return scanSkipSpace
+ }
+ ps := s.parseState[n-1]
+ switch ps {
+ case parseObjectKey:
+ if c == ':' {
+ s.parseState[n-1] = parseObjectValue
+ s.step = stateBeginValue
+ return scanObjectKey
+ }
+ return s.error(c, "after object key")
+ case parseObjectValue:
+ if c == ',' {
+ s.parseState[n-1] = parseObjectKey
+ s.step = stateBeginStringOrEmpty
+ return scanObjectValue
+ }
+ if c == '}' {
+ s.popParseState()
+ return scanEndObject
+ }
+ return s.error(c, "after object key:value pair")
+ case parseArrayValue:
+ if c == ',' {
+ s.step = stateBeginValueOrEmpty
+ return scanArrayValue
+ }
+ if c == ']' {
+ s.popParseState()
+ return scanEndArray
+ }
+ return s.error(c, "after array element")
+ case parseParam:
+ if c == ',' {
+ s.step = stateBeginValue
+ return scanParam
+ }
+ if c == ')' {
+ s.popParseState()
+ return scanEndParams
+ }
+ return s.error(c, "after array element")
+ }
+ return s.error(c, "")
+}
+
+// stateEndTop is the state after finishing the top-level value,
+// such as after reading `{}` or `[1,2,3]`.
+// Only space characters should be seen now.
+func stateEndTop(s *scanner, c byte) int {
+ if c != ' ' && c != '\t' && c != '\r' && c != '\n' {
+ // Complain about non-space byte on next call.
+ s.error(c, "after top-level value")
+ }
+ return scanEnd
+}
+
+// stateInString is the state after reading `"`.
+func stateInString(s *scanner, c byte) int {
+ if c == '"' {
+ s.step = stateEndValue
+ return scanContinue
+ }
+ if c == '\\' {
+ s.step = stateInStringEsc
+ return scanContinue
+ }
+ if c < 0x20 {
+ return s.error(c, "in string literal")
+ }
+ return scanContinue
+}
+
+// stateInStringEsc is the state after reading `"\` during a quoted string.
+func stateInStringEsc(s *scanner, c byte) int {
+ switch c {
+ case 'b', 'f', 'n', 'r', 't', '\\', '/', '"':
+ s.step = stateInString
+ return scanContinue
+ case 'u':
+ s.step = stateInStringEscU
+ return scanContinue
+ }
+ return s.error(c, "in string escape code")
+}
+
+// stateInStringEscU is the state after reading `"\u` during a quoted string.
+func stateInStringEscU(s *scanner, c byte) int {
+ if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
+ s.step = stateInStringEscU1
+ return scanContinue
+ }
+ // numbers
+ return s.error(c, "in \\u hexadecimal character escape")
+}
+
+// stateInStringEscU1 is the state after reading `"\u1` during a quoted string.
+func stateInStringEscU1(s *scanner, c byte) int {
+ if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
+ s.step = stateInStringEscU12
+ return scanContinue
+ }
+ // numbers
+ return s.error(c, "in \\u hexadecimal character escape")
+}
+
+// stateInStringEscU12 is the state after reading `"\u12` during a quoted string.
+func stateInStringEscU12(s *scanner, c byte) int {
+ if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
+ s.step = stateInStringEscU123
+ return scanContinue
+ }
+ // numbers
+ return s.error(c, "in \\u hexadecimal character escape")
+}
+
+// stateInStringEscU123 is the state after reading `"\u123` during a quoted string.
+func stateInStringEscU123(s *scanner, c byte) int {
+ if '0' <= c && c <= '9' || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' {
+ s.step = stateInString
+ return scanContinue
+ }
+ // numbers
+ return s.error(c, "in \\u hexadecimal character escape")
+}
+
+// stateNeg is the state after reading `-` during a number.
+func stateNeg(s *scanner, c byte) int {
+ if c == '0' {
+ s.step = state0
+ return scanContinue
+ }
+ if '1' <= c && c <= '9' {
+ s.step = state1
+ return scanContinue
+ }
+ return s.error(c, "in numeric literal")
+}
+
+// state1 is the state after reading a non-zero integer during a number,
+// such as after reading `1` or `100` but not `0`.
+func state1(s *scanner, c byte) int {
+ if '0' <= c && c <= '9' {
+ s.step = state1
+ return scanContinue
+ }
+ return state0(s, c)
+}
+
+// state0 is the state after reading `0` during a number.
+func state0(s *scanner, c byte) int {
+ if c == '.' {
+ s.step = stateDot
+ return scanContinue
+ }
+ if c == 'e' || c == 'E' {
+ s.step = stateE
+ return scanContinue
+ }
+ return stateEndValue(s, c)
+}
+
+// stateDot is the state after reading the integer and decimal point in a number,
+// such as after reading `1.`.
+func stateDot(s *scanner, c byte) int {
+ if '0' <= c && c <= '9' {
+ s.step = stateDot0
+ return scanContinue
+ }
+ return s.error(c, "after decimal point in numeric literal")
+}
+
+// stateDot0 is the state after reading the integer, decimal point, and subsequent
+// digits of a number, such as after reading `3.14`.
+func stateDot0(s *scanner, c byte) int {
+ if '0' <= c && c <= '9' {
+ return scanContinue
+ }
+ if c == 'e' || c == 'E' {
+ s.step = stateE
+ return scanContinue
+ }
+ return stateEndValue(s, c)
+}
+
+// stateE is the state after reading the mantissa and e in a number,
+// such as after reading `314e` or `0.314e`.
+func stateE(s *scanner, c byte) int {
+ if c == '+' || c == '-' {
+ s.step = stateESign
+ return scanContinue
+ }
+ return stateESign(s, c)
+}
+
+// stateESign is the state after reading the mantissa, e, and sign in a number,
+// such as after reading `314e-` or `0.314e+`.
+func stateESign(s *scanner, c byte) int {
+ if '0' <= c && c <= '9' {
+ s.step = stateE0
+ return scanContinue
+ }
+ return s.error(c, "in exponent of numeric literal")
+}
+
+// stateE0 is the state after reading the mantissa, e, optional sign,
+// and at least one digit of the exponent in a number,
+// such as after reading `314e-2` or `0.314e+1` or `3.14e0`.
+func stateE0(s *scanner, c byte) int {
+ if '0' <= c && c <= '9' {
+ return scanContinue
+ }
+ return stateEndValue(s, c)
+}
+
+// stateNew0 is the state after reading `n`.
+func stateNew0(s *scanner, c byte) int {
+ if c == 'e' {
+ s.step = stateNew1
+ return scanContinue
+ }
+ s.step = stateName
+ return stateName(s, c)
+}
+
+// stateNew1 is the state after reading `ne`.
+func stateNew1(s *scanner, c byte) int {
+ if c == 'w' {
+ s.step = stateNew2
+ return scanContinue
+ }
+ s.step = stateName
+ return stateName(s, c)
+}
+
+// stateNew2 is the state after reading `new`.
+func stateNew2(s *scanner, c byte) int {
+ s.step = stateName
+ if c == ' ' {
+ return scanContinue
+ }
+ return stateName(s, c)
+}
+
+// stateName is the state while reading an unquoted function name.
+func stateName(s *scanner, c byte) int {
+ if isName(c) {
+ return scanContinue
+ }
+ if c == '(' {
+ s.step = stateParamOrEmpty
+ s.pushParseState(parseParam)
+ return scanParam
+ }
+ return stateEndValue(s, c)
+}
+
+// stateParamOrEmpty is the state after reading `(`.
+func stateParamOrEmpty(s *scanner, c byte) int {
+ if c <= ' ' && isSpace(c) {
+ return scanSkipSpace
+ }
+ if c == ')' {
+ return stateEndValue(s, c)
+ }
+ return stateBeginValue(s, c)
+}
+
+// stateT is the state after reading `t`.
+func stateT(s *scanner, c byte) int {
+ if c == 'r' {
+ s.step = stateTr
+ return scanContinue
+ }
+ return s.error(c, "in literal true (expecting 'r')")
+}
+
+// stateTr is the state after reading `tr`.
+func stateTr(s *scanner, c byte) int {
+ if c == 'u' {
+ s.step = stateTru
+ return scanContinue
+ }
+ return s.error(c, "in literal true (expecting 'u')")
+}
+
+// stateTru is the state after reading `tru`.
+func stateTru(s *scanner, c byte) int {
+ if c == 'e' {
+ s.step = stateEndValue
+ return scanContinue
+ }
+ return s.error(c, "in literal true (expecting 'e')")
+}
+
+// stateF is the state after reading `f`.
+func stateF(s *scanner, c byte) int {
+ if c == 'a' {
+ s.step = stateFa
+ return scanContinue
+ }
+ return s.error(c, "in literal false (expecting 'a')")
+}
+
+// stateFa is the state after reading `fa`.
+func stateFa(s *scanner, c byte) int {
+ if c == 'l' {
+ s.step = stateFal
+ return scanContinue
+ }
+ return s.error(c, "in literal false (expecting 'l')")
+}
+
+// stateFal is the state after reading `fal`.
+func stateFal(s *scanner, c byte) int {
+ if c == 's' {
+ s.step = stateFals
+ return scanContinue
+ }
+ return s.error(c, "in literal false (expecting 's')")
+}
+
+// stateFals is the state after reading `fals`.
+func stateFals(s *scanner, c byte) int {
+ if c == 'e' {
+ s.step = stateEndValue
+ return scanContinue
+ }
+ return s.error(c, "in literal false (expecting 'e')")
+}
+
+// stateN is the state after reading `n`.
+func stateN(s *scanner, c byte) int {
+ if c == 'u' {
+ s.step = stateNu
+ return scanContinue
+ }
+ return s.error(c, "in literal null (expecting 'u')")
+}
+
+// stateNu is the state after reading `nu`.
+func stateNu(s *scanner, c byte) int {
+ if c == 'l' {
+ s.step = stateNul
+ return scanContinue
+ }
+ return s.error(c, "in literal null (expecting 'l')")
+}
+
+// stateNul is the state after reading `nul`.
+func stateNul(s *scanner, c byte) int {
+ if c == 'l' {
+ s.step = stateEndValue
+ return scanContinue
+ }
+ return s.error(c, "in literal null (expecting 'l')")
+}
+
+// stateError is the state after reaching a syntax error,
+// such as after reading `[1}` or `5.1.2`.
+func stateError(s *scanner, c byte) int {
+ return scanError
+}
+
+// error records an error and switches to the error state.
+func (s *scanner) error(c byte, context string) int {
+ s.step = stateError
+ s.err = &SyntaxError{"invalid character " + quoteChar(c) + " " + context, s.bytes}
+ return scanError
+}
+
+// quoteChar formats c as a quoted character literal
+func quoteChar(c byte) string {
+ // special cases - different from quoted strings
+ if c == '\'' {
+ return `'\''`
+ }
+ if c == '"' {
+ return `'"'`
+ }
+
+ // use quoted string with different quotation marks
+ s := strconv.Quote(string(c))
+ return "'" + s[1:len(s)-1] + "'"
+}
+
+// undo causes the scanner to return scanCode from the next state transition.
+// This gives callers a simple 1-byte undo mechanism.
+func (s *scanner) undo(scanCode int) {
+ if s.redo {
+ panic("json: invalid use of scanner")
+ }
+ s.redoCode = scanCode
+ s.redoState = s.step
+ s.step = stateRedo
+ s.redo = true
+}
+
+// stateRedo helps implement the scanner's 1-byte undo.
+func stateRedo(s *scanner, c byte) int {
+ s.redo = false
+ s.step = s.redoState
+ return s.redoCode
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-29 10:34:15 +0000