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+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.
+// http://code.google.com/p/protobuf/
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Author: kenton@google.com (Kenton Varda)
+// Based on original Protocol Buffers design by
+// Sanjay Ghemawat, Jeff Dean, and others.
+//
+// Here we have a hand-written lexer. At first you might ask yourself,
+// "Hand-written text processing? Is Kenton crazy?!" Well, first of all,
+// yes I am crazy, but that's beside the point. There are actually reasons
+// why I ended up writing this this way.
+//
+// The traditional approach to lexing is to use lex to generate a lexer for
+// you. Unfortunately, lex's output is ridiculously ugly and difficult to
+// integrate cleanly with C++ code, especially abstract code or code meant
+// as a library. Better parser-generators exist but would add dependencies
+// which most users won't already have, which we'd like to avoid. (GNU flex
+// has a C++ output option, but it's still ridiculously ugly, non-abstract,
+// and not library-friendly.)
+//
+// The next approach that any good software engineer should look at is to
+// use regular expressions. And, indeed, I did. I have code which
+// implements this same class using regular expressions. It's about 200
+// lines shorter. However:
+// - Rather than error messages telling you "This string has an invalid
+// escape sequence at line 5, column 45", you get error messages like
+// "Parse error on line 5". Giving more precise errors requires adding
+// a lot of code that ends up basically as complex as the hand-coded
+// version anyway.
+// - The regular expression to match a string literal looks like this:
+// kString = new RE("(\"([^\"\\\\]|" // non-escaped
+// "\\\\[abfnrtv?\"'\\\\0-7]|" // normal escape
+// "\\\\x[0-9a-fA-F])*\"|" // hex escape
+// "\'([^\'\\\\]|" // Also support single-quotes.
+// "\\\\[abfnrtv?\"'\\\\0-7]|"
+// "\\\\x[0-9a-fA-F])*\')");
+// Verifying the correctness of this line noise is actually harder than
+// verifying the correctness of ConsumeString(), defined below. I'm not
+// even confident that the above is correct, after staring at it for some
+// time.
+// - PCRE is fast, but there's still more overhead involved than the code
+// below.
+// - Sadly, regular expressions are not part of the C standard library, so
+// using them would require depending on some other library. For the
+// open source release, this could be really annoying. Nobody likes
+// downloading one piece of software just to find that they need to
+// download something else to make it work, and in all likelihood
+// people downloading Protocol Buffers will already be doing so just
+// to make something else work. We could include a copy of PCRE with
+// our code, but that obligates us to keep it up-to-date and just seems
+// like a big waste just to save 200 lines of code.
+//
+// On a similar but unrelated note, I'm even scared to use ctype.h.
+// Apparently functions like isalpha() are locale-dependent. So, if we used
+// that, then if this code is being called from some program that doesn't
+// have its locale set to "C", it would behave strangely. We can't just set
+// the locale to "C" ourselves since we might break the calling program that
+// way, particularly if it is multi-threaded. WTF? Someone please let me
+// (Kenton) know if I'm missing something here...
+//
+// I'd love to hear about other alternatives, though, as this code isn't
+// exactly pretty.
+
+#include <google/protobuf/io/tokenizer.h>
+#include <google/protobuf/io/zero_copy_stream.h>
+#include <google/protobuf/stubs/strutil.h>
+
+namespace google {
+namespace protobuf {
+namespace io {
+namespace {
+
+// As mentioned above, I don't trust ctype.h due to the presence of "locales".
+// So, I have written replacement functions here. Someone please smack me if
+// this is a bad idea or if there is some way around this.
+//
+// These "character classes" are designed to be used in template methods.
+// For instance, Tokenizer::ConsumeZeroOrMore<Whitespace>() will eat
+// whitespace.
+
+// Note: No class is allowed to contain '\0', since this is used to mark end-
+// of-input and is handled specially.
+
+#define CHARACTER_CLASS(NAME, EXPRESSION) \
+ class NAME { \
+ public: \
+ static inline bool InClass(char c) { \
+ return EXPRESSION; \
+ } \
+ }
+
+CHARACTER_CLASS(Whitespace, c == ' ' || c == '\n' || c == '\t' ||
+ c == '\r' || c == '\v');
+
+CHARACTER_CLASS(Unprintable, c < ' ' && c != '\0');
+
+CHARACTER_CLASS(Digit, '0' <= c && c <= '9');
+CHARACTER_CLASS(OctalDigit, '0' <= c && c <= '7');
+CHARACTER_CLASS(HexDigit, ('0' <= c && c <= '9') ||
+ ('a' <= c && c <= 'f') ||
+ ('A' <= c && c <= 'F'));
+
+CHARACTER_CLASS(Letter, ('a' <= c && c <= 'z') ||
+ ('A' <= c && c <= 'Z') ||
+ (c == '_'));
+
+CHARACTER_CLASS(Alphanumeric, ('a' <= c && c <= 'z') ||
+ ('A' <= c && c <= 'Z') ||
+ ('0' <= c && c <= '9') ||
+ (c == '_'));
+
+CHARACTER_CLASS(Escape, c == 'a' || c == 'b' || c == 'f' || c == 'n' ||
+ c == 'r' || c == 't' || c == 'v' || c == '\\' ||
+ c == '?' || c == '\'' || c == '\"');
+
+#undef CHARACTER_CLASS
+
+// Given a char, interpret it as a numeric digit and return its value.
+// This supports any number base up to 36.
+inline int DigitValue(char digit) {
+ if ('0' <= digit && digit <= '9') return digit - '0';
+ if ('a' <= digit && digit <= 'z') return digit - 'a' + 10;
+ if ('A' <= digit && digit <= 'Z') return digit - 'A' + 10;
+ return -1;
+}
+
+// Inline because it's only used in one place.
+inline char TranslateEscape(char c) {
+ switch (c) {
+ case 'a': return '\a';
+ case 'b': return '\b';
+ case 'f': return '\f';
+ case 'n': return '\n';
+ case 'r': return '\r';
+ case 't': return '\t';
+ case 'v': return '\v';
+ case '\\': return '\\';
+ case '?': return '\?'; // Trigraphs = :(
+ case '\'': return '\'';
+ case '"': return '\"';
+
+ // We expect escape sequences to have been validated separately.
+ default: return '?';
+ }
+}
+
+} // anonymous namespace
+
+ErrorCollector::~ErrorCollector() {}
+
+// ===================================================================
+
+Tokenizer::Tokenizer(ZeroCopyInputStream* input,
+ ErrorCollector* error_collector)
+ : input_(input),
+ error_collector_(error_collector),
+ buffer_(NULL),
+ buffer_size_(0),
+ buffer_pos_(0),
+ read_error_(false),
+ line_(0),
+ column_(0),
+ token_start_(-1),
+ allow_f_after_float_(false),
+ comment_style_(CPP_COMMENT_STYLE) {
+
+ current_.line = 0;
+ current_.column = 0;
+ current_.type = TYPE_START;
+
+ Refresh();
+}
+
+Tokenizer::~Tokenizer() {
+ // If we had any buffer left unread, return it to the underlying stream
+ // so that someone else can read it.
+ if (buffer_size_ > buffer_pos_) {
+ input_->BackUp(buffer_size_ - buffer_pos_);
+ }
+}
+
+// -------------------------------------------------------------------
+// Internal helpers.
+
+void Tokenizer::NextChar() {
+ // Update our line and column counters based on the character being
+ // consumed.
+ if (current_char_ == '\n') {
+ ++line_;
+ column_ = 0;
+ } else if (current_char_ == '\t') {
+ column_ += kTabWidth - column_ % kTabWidth;
+ } else {
+ ++column_;
+ }
+
+ // Advance to the next character.
+ ++buffer_pos_;
+ if (buffer_pos_ < buffer_size_) {
+ current_char_ = buffer_[buffer_pos_];
+ } else {
+ Refresh();
+ }
+}
+
+void Tokenizer::Refresh() {
+ if (read_error_) {
+ current_char_ = '\0';
+ return;
+ }
+
+ // If we're in a token, append the rest of the buffer to it.
+ if (token_start_ >= 0 && token_start_ < buffer_size_) {
+ current_.text.append(buffer_ + token_start_, buffer_size_ - token_start_);
+ token_start_ = 0;
+ }
+
+ const void* data = NULL;
+ buffer_ = NULL;
+ buffer_pos_ = 0;
+ do {
+ if (!input_->Next(&data, &buffer_size_)) {
+ // end of stream (or read error)
+ buffer_size_ = 0;
+ read_error_ = true;
+ current_char_ = '\0';
+ return;
+ }
+ } while (buffer_size_ == 0);
+
+ buffer_ = static_cast<const char*>(data);
+
+ current_char_ = buffer_[0];
+}
+
+inline void Tokenizer::StartToken() {
+ token_start_ = buffer_pos_;
+ current_.type = TYPE_START; // Just for the sake of initializing it.
+ current_.text.clear();
+ current_.line = line_;
+ current_.column = column_;
+}
+
+inline void Tokenizer::EndToken() {
+ // Note: The if() is necessary because some STL implementations crash when
+ // you call string::append(NULL, 0), presumably because they are trying to
+ // be helpful by detecting the NULL pointer, even though there's nothing
+ // wrong with reading zero bytes from NULL.
+ if (buffer_pos_ != token_start_) {
+ current_.text.append(buffer_ + token_start_, buffer_pos_ - token_start_);
+ }
+ token_start_ = -1;
+}
+
+// -------------------------------------------------------------------
+// Helper methods that consume characters.
+
+template<typename CharacterClass>
+inline bool Tokenizer::LookingAt() {
+ return CharacterClass::InClass(current_char_);
+}
+
+template<typename CharacterClass>
+inline bool Tokenizer::TryConsumeOne() {
+ if (CharacterClass::InClass(current_char_)) {
+ NextChar();
+ return true;
+ } else {
+ return false;
+ }
+}
+
+inline bool Tokenizer::TryConsume(char c) {
+ if (current_char_ == c) {
+ NextChar();
+ return true;
+ } else {
+ return false;
+ }
+}
+
+template<typename CharacterClass>
+inline void Tokenizer::ConsumeZeroOrMore() {
+ while (CharacterClass::InClass(current_char_)) {
+ NextChar();
+ }
+}
+
+template<typename CharacterClass>
+inline void Tokenizer::ConsumeOneOrMore(const char* error) {
+ if (!CharacterClass::InClass(current_char_)) {
+ AddError(error);
+ } else {
+ do {
+ NextChar();
+ } while (CharacterClass::InClass(current_char_));
+ }
+}
+
+// -------------------------------------------------------------------
+// Methods that read whole patterns matching certain kinds of tokens
+// or comments.
+
+void Tokenizer::ConsumeString(char delimiter) {
+ while (true) {
+ switch (current_char_) {
+ case '\0':
+ case '\n': {
+ AddError("String literals cannot cross line boundaries.");
+ return;
+ }
+
+ case '\\': {
+ // An escape sequence.
+ NextChar();
+ if (TryConsumeOne<Escape>()) {
+ // Valid escape sequence.
+ } else if (TryConsumeOne<OctalDigit>()) {
+ // Possibly followed by two more octal digits, but these will
+ // just be consumed by the main loop anyway so we don't need
+ // to do so explicitly here.
+ } else if (TryConsume('x') || TryConsume('X')) {
+ if (!TryConsumeOne<HexDigit>()) {
+ AddError("Expected hex digits for escape sequence.");
+ }
+ // Possibly followed by another hex digit, but again we don't care.
+ } else {
+ AddError("Invalid escape sequence in string literal.");
+ }
+ break;
+ }
+
+ default: {
+ if (current_char_ == delimiter) {
+ NextChar();
+ return;
+ }
+ NextChar();
+ break;
+ }
+ }
+ }
+}
+
+Tokenizer::TokenType Tokenizer::ConsumeNumber(bool started_with_zero,
+ bool started_with_dot) {
+ bool is_float = false;
+
+ if (started_with_zero && (TryConsume('x') || TryConsume('X'))) {
+ // A hex number (started with "0x").
+ ConsumeOneOrMore<HexDigit>("\"0x\" must be followed by hex digits.");
+
+ } else if (started_with_zero && LookingAt<Digit>()) {
+ // An octal number (had a leading zero).
+ ConsumeZeroOrMore<OctalDigit>();
+ if (LookingAt<Digit>()) {
+ AddError("Numbers starting with leading zero must be in octal.");
+ ConsumeZeroOrMore<Digit>();
+ }
+
+ } else {
+ // A decimal number.
+ if (started_with_dot) {
+ is_float = true;
+ ConsumeZeroOrMore<Digit>();
+ } else {
+ ConsumeZeroOrMore<Digit>();
+
+ if (TryConsume('.')) {
+ is_float = true;
+ ConsumeZeroOrMore<Digit>();
+ }
+ }
+
+ if (TryConsume('e') || TryConsume('E')) {
+ is_float = true;
+ TryConsume('-') || TryConsume('+');
+ ConsumeOneOrMore<Digit>("\"e\" must be followed by exponent.");
+ }
+
+ if (allow_f_after_float_ && (TryConsume('f') || TryConsume('F'))) {
+ is_float = true;
+ }
+ }
+
+ if (LookingAt<Letter>()) {
+ AddError("Need space between number and identifier.");
+ } else if (current_char_ == '.') {
+ if (is_float) {
+ AddError(
+ "Already saw decimal point or exponent; can't have another one.");
+ } else {
+ AddError("Hex and octal numbers must be integers.");
+ }
+ }
+
+ return is_float ? TYPE_FLOAT : TYPE_INTEGER;
+}
+
+void Tokenizer::ConsumeLineComment() {
+ while (current_char_ != '\0' && current_char_ != '\n') {
+ NextChar();
+ }
+ TryConsume('\n');
+}
+
+void Tokenizer::ConsumeBlockComment() {
+ int start_line = line_;
+ int start_column = column_ - 2;
+
+ while (true) {
+ while (current_char_ != '\0' &&
+ current_char_ != '*' &&
+ current_char_ != '/') {
+ NextChar();
+ }
+
+ if (TryConsume('*') && TryConsume('/')) {
+ // End of comment.
+ break;
+ } else if (TryConsume('/') && current_char_ == '*') {
+ // Note: We didn't consume the '*' because if there is a '/' after it
+ // we want to interpret that as the end of the comment.
+ AddError(
+ "\"/*\" inside block comment. Block comments cannot be nested.");
+ } else if (current_char_ == '\0') {
+ AddError("End-of-file inside block comment.");
+ error_collector_->AddError(
+ start_line, start_column, " Comment started here.");
+ break;
+ }
+ }
+}
+
+// -------------------------------------------------------------------
+
+bool Tokenizer::Next() {
+ TokenType last_token_type = current_.type;
+
+ // Did we skip any characters after the last token?
+ bool skipped_stuff = false;
+
+ while (!read_error_) {
+ if (TryConsumeOne<Whitespace>()) {
+ ConsumeZeroOrMore<Whitespace>();
+
+ } else if (comment_style_ == CPP_COMMENT_STYLE && TryConsume('/')) {
+ // Starting a comment?
+ if (TryConsume('/')) {
+ ConsumeLineComment();
+ } else if (TryConsume('*')) {
+ ConsumeBlockComment();
+ } else {
+ // Oops, it was just a slash. Return it.
+ current_.type = TYPE_SYMBOL;
+ current_.text = "/";
+ current_.line = line_;
+ current_.column = column_ - 1;
+ return true;
+ }
+
+ } else if (comment_style_ == SH_COMMENT_STYLE && TryConsume('#')) {
+ ConsumeLineComment();
+
+ } else if (LookingAt<Unprintable>() || current_char_ == '\0') {
+ AddError("Invalid control characters encountered in text.");
+ NextChar();
+ // Skip more unprintable characters, too. But, remember that '\0' is
+ // also what current_char_ is set to after EOF / read error. We have
+ // to be careful not to go into an infinite loop of trying to consume
+ // it, so make sure to check read_error_ explicitly before consuming
+ // '\0'.
+ while (TryConsumeOne<Unprintable>() ||
+ (!read_error_ && TryConsume('\0'))) {
+ // Ignore.
+ }
+
+ } else {
+ // Reading some sort of token.
+ StartToken();
+
+ if (TryConsumeOne<Letter>()) {
+ ConsumeZeroOrMore<Alphanumeric>();
+ current_.type = TYPE_IDENTIFIER;
+ } else if (TryConsume('0')) {
+ current_.type = ConsumeNumber(true, false);
+ } else if (TryConsume('.')) {
+ // This could be the beginning of a floating-point number, or it could
+ // just be a '.' symbol.
+
+ if (TryConsumeOne<Digit>()) {
+ // It's a floating-point number.
+ if (last_token_type == TYPE_IDENTIFIER && !skipped_stuff) {
+ // We don't accept syntax like "blah.123".
+ error_collector_->AddError(line_, column_ - 2,
+ "Need space between identifier and decimal point.");
+ }
+ current_.type = ConsumeNumber(false, true);
+ } else {
+ current_.type = TYPE_SYMBOL;
+ }
+ } else if (TryConsumeOne<Digit>()) {
+ current_.type = ConsumeNumber(false, false);
+ } else if (TryConsume('\"')) {
+ ConsumeString('\"');
+ current_.type = TYPE_STRING;
+ } else if (TryConsume('\'')) {
+ ConsumeString('\'');
+ current_.type = TYPE_STRING;
+ } else {
+ NextChar();
+ current_.type = TYPE_SYMBOL;
+ }
+
+ EndToken();
+ return true;
+ }
+
+ skipped_stuff = true;
+ }
+
+ // EOF
+ current_.type = TYPE_END;
+ current_.text.clear();
+ current_.line = line_;
+ current_.column = column_;
+ return false;
+}
+
+// -------------------------------------------------------------------
+// Token-parsing helpers. Remember that these don't need to report
+// errors since any errors should already have been reported while
+// tokenizing. Also, these can assume that whatever text they
+// are given is text that the tokenizer actually parsed as a token
+// of the given type.
+
+bool Tokenizer::ParseInteger(const string& text, uint64 max_value,
+ uint64* output) {
+ // Sadly, we can't just use strtoul() since it is only 32-bit and strtoull()
+ // is non-standard. I hate the C standard library. :(
+
+// return strtoull(text.c_str(), NULL, 0);
+
+ const char* ptr = text.c_str();
+ int base = 10;
+ if (ptr[0] == '0') {
+ if (ptr[1] == 'x') {
+ // This is hex.
+ base = 16;
+ ptr += 2;
+ } else {
+ // This is octal.
+ base = 8;
+ }
+ }
+
+ uint64 result = 0;
+ for (; *ptr != '\0'; ptr++) {
+ int digit = DigitValue(*ptr);
+ GOOGLE_LOG_IF(DFATAL, digit < 0 || digit >= base)
+ << " Tokenizer::ParseInteger() passed text that could not have been"
+ " tokenized as an integer: " << CEscape(text);
+ if (digit > max_value || result > (max_value - digit) / base) {
+ // Overflow.
+ return false;
+ }
+ result = result * base + digit;
+ }
+
+ *output = result;
+ return true;
+}
+
+double Tokenizer::ParseFloat(const string& text) {
+ const char* start = text.c_str();
+ char* end;
+ double result = NoLocaleStrtod(start, &end);
+
+ // "1e" is not a valid float, but if the tokenizer reads it, it will
+ // report an error but still return it as a valid token. We need to
+ // accept anything the tokenizer could possibly return, error or not.
+ if (*end == 'e' || *end == 'E') {
+ ++end;
+ if (*end == '-' || *end == '+') ++end;
+ }
+
+ // If the Tokenizer had allow_f_after_float_ enabled, the float may be
+ // suffixed with the letter 'f'.
+ if (*end == 'f' || *end == 'F') {
+ ++end;
+ }
+
+ GOOGLE_LOG_IF(DFATAL, end - start != text.size() || *start == '-')
+ << " Tokenizer::ParseFloat() passed text that could not have been"
+ " tokenized as a float: " << CEscape(text);
+ return result;
+}
+
+void Tokenizer::ParseString(const string& text, string* output) {
+ output->clear();
+
+ // Reminder: text[0] is always the quote character. (If text is
+ // empty, it's invalid, so we'll just return.)
+ if (text.empty()) {
+ GOOGLE_LOG(DFATAL)
+ << " ParseString::ParseString() passed text that could not have been"
+ " tokenized as a string: " << CEscape(text);
+ return;
+ }
+
+ output->reserve(text.size());
+
+ // Loop through the string copying characters to "output" and
+ // interpreting escape sequences. Note that any invalid escape
+ // sequences or other errors were already reported while tokenizing.
+ // In this case we do not need to produce valid results.
+ for (const char* ptr = text.c_str() + 1; *ptr != '\0'; ptr++) {
+ if (*ptr == '\\' && ptr[1] != '\0') {
+ // An escape sequence.
+ ++ptr;
+
+ if (OctalDigit::InClass(*ptr)) {
+ // An octal escape. May one, two, or three digits.
+ int code = DigitValue(*ptr);
+ if (OctalDigit::InClass(ptr[1])) {
+ ++ptr;
+ code = code * 8 + DigitValue(*ptr);
+ }
+ if (OctalDigit::InClass(ptr[1])) {
+ ++ptr;
+ code = code * 8 + DigitValue(*ptr);
+ }
+ output->push_back(static_cast<char>(code));
+
+ } else if (*ptr == 'x') {
+ // A hex escape. May zero, one, or two digits. (The zero case
+ // will have been caught as an error earlier.)
+ int code = 0;
+ if (HexDigit::InClass(ptr[1])) {
+ ++ptr;
+ code = DigitValue(*ptr);
+ }
+ if (HexDigit::InClass(ptr[1])) {
+ ++ptr;
+ code = code * 16 + DigitValue(*ptr);
+ }
+ output->push_back(static_cast<char>(code));
+
+ } else {
+ // Some other escape code.
+ output->push_back(TranslateEscape(*ptr));
+ }
+
+ } else if (*ptr == text[0]) {
+ // Ignore quote matching the starting quote.
+ } else {
+ output->push_back(*ptr);
+ }
+ }
+
+ return;
+}
+
+} // namespace io
+} // namespace protobuf
+} // namespace google
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