tree-sitter/spec/runtime/helpers/spy_input.cc
2015-09-19 13:29:30 -07:00

101 lines
2.7 KiB
C++

#include "runtime/helpers/spy_input.h"
#include <string.h>
#include <algorithm>
#include "utf8proc.h"
using std::string;
static const size_t UTF8_MAX_CHAR_SIZE = 4;
static long byte_for_character(const char *str, size_t len, size_t goal_character) {
size_t character = 0, byte = 0;
int32_t dest_char;
while (character < goal_character) {
if (byte >= len)
return -1;
byte += utf8proc_iterate(
(uint8_t *)str + byte,
len - byte,
&dest_char);
character++;
}
return byte;
}
SpyInput::SpyInput(string content, size_t chars_per_chunk) :
chars_per_chunk(chars_per_chunk),
buffer_size(UTF8_MAX_CHAR_SIZE * chars_per_chunk),
buffer(new char[buffer_size]),
byte_offset(0),
content(content),
strings_read({""}) {}
SpyInput::~SpyInput() {
delete buffer;
}
const char * SpyInput::read(void *payload, size_t *bytes_read) {
auto spy = static_cast<SpyInput *>(payload);
if (spy->byte_offset > spy->content.size()) {
*bytes_read = 0;
return "";
}
const char *start = spy->content.data() + spy->byte_offset;
long byte_count = byte_for_character(start, spy->content.size() - spy->byte_offset, spy->chars_per_chunk);
if (byte_count < 0)
byte_count = spy->content.size() - spy->byte_offset;
*bytes_read = byte_count;
spy->byte_offset += byte_count;
spy->strings_read.back() += string(start, byte_count);
/*
* This class stores its entire `content` in a contiguous buffer, but we want
* to ensure that the code under test cannot accidentally read more than
* `*bytes_read` bytes past the returned pointer. To make sure that this type
* of error does not fly, we copy the chunk into a zeroed-out buffer and
* return a reference to that buffer, rather than a pointer into the main
* content.
*/
memset(spy->buffer, 0, spy->buffer_size);
memcpy(spy->buffer, start, byte_count);
return spy->buffer;
}
int SpyInput::seek(void *payload, TSLength position) {
auto spy = static_cast<SpyInput *>(payload);
if (spy->strings_read.size() == 0 || spy->strings_read.back().size() > 0)
spy->strings_read.push_back("");
spy->byte_offset = position.bytes;
return 0;
}
TSInput SpyInput::input() {
TSInput result;
result.payload = this;
result.seek_fn = seek;
result.read_fn = read;
return result;
}
bool SpyInput::insert(size_t char_index, string text) {
long pos = byte_for_character(content.data(), content.size(), char_index);
if (pos < 0) return false;
content.insert(pos, text);
return true;
}
bool SpyInput::erase(size_t char_index, size_t len) {
long pos = byte_for_character(content.data(), content.size(), char_index);
if (pos < 0) return false;
content.erase(pos, len);
return true;
}
void SpyInput::clear() {
strings_read.clear();
}