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// Copyright 2016 The Draco Authors.
//
// 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.
//
#include "draco/io/parser_utils.h"
#include <algorithm>
#include <cctype>
#include <cmath>
#include <iterator>
namespace draco {
namespace parser {
void SkipCharacters(DecoderBuffer *buffer, const char *skip_chars) {
if (skip_chars == nullptr)
return;
const int num_skip_chars = static_cast<int>(strlen(skip_chars));
char c;
while (buffer->Peek(&c)) {
// Check all characters in the pattern.
bool skip = false;
for (int i = 0; i < num_skip_chars; ++i) {
if (c == skip_chars[i]) {
skip = true;
break;
}
}
if (!skip)
return;
buffer->Advance(1);
}
}
void SkipWhitespace(DecoderBuffer *buffer) {
bool end_reached = false;
while (PeekWhitespace(buffer, &end_reached) && !end_reached) {
// Skip the whitespace character
buffer->Advance(1);
}
}
bool PeekWhitespace(DecoderBuffer *buffer, bool *end_reached) {
uint8_t c;
if (!buffer->Peek(&c)) {
*end_reached = true;
return false; // eof reached.
}
if (!isspace(c))
return false; // Non-whitespace character reached.
return true;
}
void SkipLine(DecoderBuffer *buffer) {
char c;
while (buffer->Peek(&c)) {
// Skip the character.
buffer->Advance(1);
if (c == '\n')
return; // Return at the end of line
}
}
bool ParseFloat(DecoderBuffer *buffer, float *value) {
// Read optional sign.
char ch;
if (!buffer->Peek(&ch))
return false;
int sign = GetSignValue(ch);
if (sign != 0) {
buffer->Advance(1);
} else {
sign = 1;
}
// Parse integer component.
bool have_digits = false;
double v = 0.0;
while (buffer->Peek(&ch) && ch >= '0' && ch <= '9') {
v *= 10.0;
v += (ch - '0');
buffer->Advance(1);
have_digits = true;
}
if (ch == '.') {
// Parse fractional component.
buffer->Advance(1);
double fraction = 1.0;
while (buffer->Peek(&ch) && ch >= '0' && ch <= '9') {
fraction *= 0.1;
v += (ch - '0') * fraction;
buffer->Advance(1);
have_digits = true;
}
}
if (!have_digits) {
// Check for special constants (inf, nan, ...).
std::string text;
if (!ParseString(buffer, &text))
return false;
if (text == "inf" || text == "Inf") {
v = std::numeric_limits<double>::infinity();
} else if (text == "nan" || text == "NaN") {
v = nan("");
} else {
// Invalid string.
return false;
}
} else {
// Handle exponent if present.
if (ch == 'e' || ch == 'E') {
buffer->Advance(1); // Skip 'e' marker.
// Parse integer exponent.
int32_t exponent = 0;
if (!ParseSignedInt(buffer, &exponent))
return false;
// Apply exponent scaling to value.
v *= pow(static_cast<double>(10.0), exponent);
}
}
*value = (sign < 0) ? static_cast<float>(-v) : static_cast<float>(v);
return true;
}
bool ParseSignedInt(DecoderBuffer *buffer, int32_t *value) {
// Parse any explicit sign and set the appropriate largest magnitude
// value that can be represented without overflow.
char ch;
if (!buffer->Peek(&ch))
return false;
const int sign = GetSignValue(ch);
if (sign != 0)
buffer->Advance(1);
// Attempt to parse integer body.
uint32_t v;
if (!ParseUnsignedInt(buffer, &v))
return false;
*value = (sign < 0) ? -v : v;
return true;
}
bool ParseUnsignedInt(DecoderBuffer *buffer, uint32_t *value) {
// Parse the number until we run out of digits.
uint32_t v = 0;
char ch;
bool have_digits = false;
while (buffer->Peek(&ch) && ch >= '0' && ch <= '9') {
v *= 10;
v += (ch - '0');
buffer->Advance(1);
have_digits = true;
}
if (!have_digits)
return false;
*value = v;
return true;
}
int GetSignValue(char c) {
if (c == '-')
return -1;
if (c == '+')
return 1;
return 0;
}
bool ParseString(DecoderBuffer *buffer, std::string *out_string) {
out_string->clear();
SkipWhitespace(buffer);
bool end_reached = false;
while (!PeekWhitespace(buffer, &end_reached) && !end_reached) {
char c;
if (!buffer->Decode(&c))
return false;
*out_string += c;
}
return true;
}
void ParseLine(DecoderBuffer *buffer, std::string *out_string) {
out_string->clear();
char c;
while (buffer->Peek(&c)) {
// Skip the character.
buffer->Advance(1);
if (c == '\n')
return; // Return at the end of line.
if (c == '\r')
continue; // Ignore extra line ending characters.
*out_string += c;
}
}
DecoderBuffer ParseLineIntoDecoderBuffer(DecoderBuffer *buffer) {
const char *const head = buffer->data_head();
char c;
while (buffer->Peek(&c)) {
// Skip the character.
buffer->Advance(1);
if (c == '\n')
break; // End of the line reached.
if (c == '\r')
continue; // Ignore extra line ending characters.
}
DecoderBuffer out_buffer;
out_buffer.Init(head, buffer->data_head() - head);
return out_buffer;
}
std::string ToLower(const std::string &str) {
std::string out;
std::transform(str.begin(), str.end(), std::back_inserter(out), tolower);
return out;
}
} // namespace parser
} // namespace draco
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