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parse.go
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parse.go
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package toml
import (
"fmt"
"log"
"strconv"
"strings"
"time"
"unicode/utf8"
)
type parser struct {
mapping map[string]interface{}
types map[string]tomlType
lx *lexer
// A list of keys in the order that they appear in the TOML data.
ordered []Key
// the full key for the current hash in scope
context Key
// the base key name for everything except hashes
currentKey string
// rough approximation of line number
approxLine int
// A map of 'key.group.names' to whether they were created implicitly.
implicits map[string]bool
}
type parseError string
func (pe parseError) Error() string {
return string(pe)
}
func parse(data string) (p *parser, err error) {
defer func() {
if r := recover(); r != nil {
var ok bool
if err, ok = r.(parseError); ok {
return
}
panic(r)
}
}()
p = &parser{
mapping: make(map[string]interface{}),
types: make(map[string]tomlType),
lx: lex(data),
ordered: make([]Key, 0),
implicits: make(map[string]bool),
}
for {
item := p.next()
if item.typ == itemEOF {
break
}
p.topLevel(item)
}
return p, nil
}
func (p *parser) panic(format string, v ...interface{}) {
msg := fmt.Sprintf("Near line %d, key '%s': %s",
p.approxLine, p.current(), fmt.Sprintf(format, v...))
panic(parseError(msg))
}
func (p *parser) next() item {
it := p.lx.nextItem()
if it.typ == itemError {
p.panic("Near line %d: %s", it.line, it.val)
}
return it
}
func (p *parser) bug(format string, v ...interface{}) {
log.Fatalf("BUG: %s\n\n", fmt.Sprintf(format, v...))
}
func (p *parser) expect(typ itemType) item {
it := p.next()
p.assertEqual(typ, it.typ)
return it
}
func (p *parser) assertEqual(expected, got itemType) {
if expected != got {
p.bug("Expected '%s' but got '%s'.", expected, got)
}
}
func (p *parser) topLevel(item item) {
switch item.typ {
case itemCommentStart:
p.approxLine = item.line
p.expect(itemText)
case itemKeyGroupStart:
kg := p.expect(itemText)
p.approxLine = kg.line
key := make(Key, 0)
for ; kg.typ == itemText; kg = p.next() {
key = append(key, kg.val)
}
p.assertEqual(itemKeyGroupEnd, kg.typ)
p.establishContext(key)
p.setType("", tomlHash)
p.ordered = append(p.ordered, key)
case itemKeyStart:
kname := p.expect(itemText)
p.currentKey = kname.val
p.approxLine = kname.line
val, typ := p.value(p.next())
p.setValue(p.currentKey, val)
p.setType(p.currentKey, typ)
p.ordered = append(p.ordered, p.context.add(p.currentKey))
p.currentKey = ""
default:
p.bug("Unexpected type at top level: %s", item.typ)
}
}
// value translates an expected value from the lexer into a Go value wrapped
// as an empty interface.
func (p *parser) value(it item) (interface{}, tomlType) {
switch it.typ {
case itemString:
return p.replaceUnicode(replaceEscapes(it.val)), p.typeOfPrimitive(it)
case itemBool:
switch it.val {
case "true":
return true, p.typeOfPrimitive(it)
case "false":
return false, p.typeOfPrimitive(it)
}
p.bug("Expected boolean value, but got '%s'.", it.val)
case itemInteger:
num, err := strconv.ParseInt(it.val, 10, 64)
if err != nil {
if e, ok := err.(*strconv.NumError); ok &&
e.Err == strconv.ErrRange {
p.panic("Integer '%s' is out of the range of 64-bit "+
"signed integers.", it.val)
} else {
p.bug("Expected integer value, but got '%s'.", it.val)
}
}
return num, p.typeOfPrimitive(it)
case itemFloat:
num, err := strconv.ParseFloat(it.val, 64)
if err != nil {
if e, ok := err.(*strconv.NumError); ok &&
e.Err == strconv.ErrRange {
p.panic("Float '%s' is out of the range of 64-bit "+
"IEEE-754 floating-point numbers.", it.val)
} else {
p.bug("Expected float value, but got '%s'.", it.val)
}
}
return num, p.typeOfPrimitive(it)
case itemDatetime:
t, err := time.Parse("2006-01-02T15:04:05Z", it.val)
if err != nil {
p.bug("Expected Zulu formatted DateTime, but got '%s'.", it.val)
}
return t, p.typeOfPrimitive(it)
case itemArray:
array := make([]interface{}, 0)
types := make([]tomlType, 0)
for it = p.next(); it.typ != itemArrayEnd; it = p.next() {
if it.typ == itemCommentStart {
p.expect(itemText)
continue
}
val, typ := p.value(it)
array = append(array, val)
types = append(types, typ)
}
return array, p.typeOfArray(types)
}
p.bug("Unexpected value type: %s", it.typ)
panic("unreachable")
}
// establishContext sets the current context of the parser, where the context
// is the hash currently in scope.
//
// Establishing the context also makes sure that the key isn't a duplicate, and
// will create implicit hashes automatically.
func (p *parser) establishContext(key Key) {
var ok bool
// Always start at the top level and drill down for our context.
hashContext := p.mapping
keyContext := make(Key, 0)
// We only need implicit hashes for key[0:-1]
for _, k := range key[0 : len(key)-1] {
_, ok = hashContext[k]
keyContext = append(keyContext, k)
// No key? Make an implicit hash and move on.
if !ok {
p.addImplicit(keyContext)
hashContext[k] = make(map[string]interface{})
}
// It better be a hash, since this MUST be a key group (by virtue of
// it not being the last element in a key).
if hashContext, ok = hashContext[k].(map[string]interface{}); !ok {
p.panic("Key '%s' was already created as a hash.", keyContext)
}
}
p.context = keyContext
p.setValue(key[len(key)-1], make(map[string]interface{}))
p.context = append(p.context, key[len(key)-1])
}
// setValue sets the given key to the given value in the current context.
// It will make sure that the key hasn't already been defined, account for
// implicit key groups.
func (p *parser) setValue(key string, value interface{}) {
var tmpHash interface{}
var ok bool
hash := p.mapping
keyContext := make(Key, 0)
for _, k := range p.context {
keyContext = append(keyContext, k)
if tmpHash, ok = hash[k]; !ok {
p.bug("Context for key '%s' has not been established.", keyContext)
}
if hash, ok = tmpHash.(map[string]interface{}); !ok {
p.bug("Expected hash to have type 'map[string]interface{}', but "+
"it has '%T' instead.", tmpHash)
}
}
keyContext = append(keyContext, key)
if _, ok := hash[key]; ok {
// We need to do some fancy footwork here. If `hash[key]` was implcitly
// created AND `value` is a hash, then let this go through and stop
// tagging this keygroup as implicit.
if p.isImplicit(keyContext) {
p.removeImplicit(keyContext)
return
}
// Otherwise, we have a concrete key trying to override a previous
// key, which is *always* wrong.
p.panic("Key '%s' has already been defined.", keyContext)
}
hash[key] = value
}
// setType sets the type of a particular value at a given key.
// It should be called immediately AFTER setValue.
func (p *parser) setType(key string, typ tomlType) {
keyContext := make(Key, 0, len(p.context)+1)
for _, k := range p.context {
keyContext = append(keyContext, k)
}
if len(key) > 0 { // allow type setting for hashes
keyContext = append(keyContext, key)
}
fullkey := keyContext.String()
if _, ok := p.types[fullkey]; ok {
p.bug("Type for key '%s' has already been set, but it wasn't "+
"detected as a duplicate in setValue.", fullkey)
}
p.types[fullkey] = typ
}
// addImplicit sets the given Key as having been created implicitly.
func (p *parser) addImplicit(key Key) {
p.implicits[key.String()] = true
}
// removeImplicit stops tagging the given key as having been implicitly created.
func (p *parser) removeImplicit(key Key) {
p.implicits[key.String()] = false
}
// isImplicit returns true if the key group pointed to by the key was created
// implicitly.
func (p *parser) isImplicit(key Key) bool {
return p.implicits[key.String()]
}
// current returns the full key name of the current context.
func (p *parser) current() string {
if len(p.currentKey) == 0 {
return p.context.String()
}
if len(p.context) == 0 {
return p.currentKey
}
return fmt.Sprintf("%s.%s", p.context, p.currentKey)
}
func replaceEscapes(s string) string {
return strings.NewReplacer(
"\\b", "\u0008",
"\\t", "\u0009",
"\\n", "\u000A",
"\\f", "\u000C",
"\\r", "\u000D",
"\\\"", "\u0022",
"\\/", "\u002F",
"\\\\", "\u005C",
).Replace(s)
}
func (p *parser) replaceUnicode(s string) string {
indexEsc := func() int {
return strings.Index(s, "\\u")
}
for i := indexEsc(); i != -1; i = indexEsc() {
asciiBytes := s[i+2 : i+6]
s = strings.Replace(s, s[i:i+6], p.asciiEscapeToUnicode(asciiBytes), -1)
}
return s
}
func (p *parser) asciiEscapeToUnicode(s string) string {
hex, err := strconv.ParseUint(strings.ToLower(s), 16, 32)
if err != nil {
p.bug("Could not parse '%s' as a hexadecimal number, but the "+
"lexer claims it's OK: %s", s, err)
}
// I honestly don't understand how this works. I can't seem to find
// a way to make this fail. I figured this would fail on invalid UTF-8
// characters like U+DCFF, but it doesn't.
r := string(rune(hex))
if !utf8.ValidString(r) {
p.panic("Escaped character '\\u%s' is not valid UTF-8.", s)
}
return string(r)
}