calibre/src/calibre/srv/html_as_json.cpp
2019-10-29 15:58:24 +05:30

478 lines
13 KiB
C++

/*
* html_as_json.cpp
* Copyright (C) 2019 Kovid Goyal <kovid at kovidgoyal.net>
*
* Distributed under terms of the GPL3 license.
*/
#include <Python.h>
#include <algorithm>
#include <cstdint>
#include <cstring>
#include <vector>
#include <stack>
#include <string>
#include <memory>
struct PyObjectDeleter {
void operator()(PyObject *obj) {
Py_XDECREF(obj);
}
};
// unique_ptr that uses Py_XDECREF as the destructor function.
typedef std::unique_ptr<PyObject, PyObjectDeleter> pyunique_ptr;
#define write_str_literal(x) this->write_data(x, sizeof(x)-1)
#define UTF8_ACCEPT 0
#define UTF8_REJECT 1
static const uint8_t utf8d[] = {
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 00..1f
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 20..3f
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 40..5f
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 60..7f
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, // 80..9f
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, // a0..bf
8,8,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, // c0..df
0xa,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x3,0x4,0x3,0x3, // e0..ef
0xb,0x6,0x6,0x6,0x5,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8,0x8, // f0..ff
0x0,0x1,0x2,0x3,0x5,0x8,0x7,0x1,0x1,0x1,0x4,0x6,0x1,0x1,0x1,0x1, // s0..s0
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,1,1,0,1,0,1,1,1,1,1,1, // s1..s2
1,2,1,1,1,1,1,2,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1, // s3..s4
1,2,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,3,1,3,1,1,1,1,1,1, // s5..s6
1,3,1,1,1,1,1,3,1,3,1,1,1,1,1,1,1,3,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // s7..s8
};
static inline void
utf8_decode_(uint32_t* state, uint32_t* codep, uint8_t byte) {
/* Comes from http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
* Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
* Used under license: https://opensource.org/licenses/MIT
*/
uint32_t type = utf8d[byte];
*codep = (*state != UTF8_ACCEPT) ?
(byte & 0x3fu) | (*codep << 6) :
(0xff >> type) & (byte);
*state = utf8d[256 + *state*16 + type];
}
static inline unsigned
utf8_read_char(const char *s, uint32_t *codep) {
unsigned len = 0;
uint32_t state = UTF8_ACCEPT;
while(true) {
utf8_decode_(&state, codep, s[len++]);
if (state == UTF8_ACCEPT) break;
else if (state == UTF8_REJECT) { return 0; }
}
return len;
}
static inline void
to_surrogate_pair(uint32_t unicode, uint16_t *uc, uint16_t *lc) {
uint32_t n = unicode - 0x10000;
*uc = ((n >> 10) & 0x3FF) | 0xD800;
*lc = (n & 0x3FF) | 0xDC00;
}
static inline unsigned
write_hex16(char *out, uint16_t val) {
static const char *hex = "0123456789ABCDEF";
*out++ = hex[(val >> 12) & 0xF];
*out++ = hex[(val >> 8) & 0xF];
*out++ = hex[(val >> 4) & 0xF];
*out++ = hex[ val & 0xF];
return 4;
}
static inline bool
namespaces_are_equal(const char *a, const char *b, size_t len) {
for (size_t i = 0; i < len; i++) {
if (a[i] != b[i]) return false;
if (!b[i]) return true;
}
return true;
}
class StringOrNone {
PyObject *temp, *orig;
const char *data;
public:
StringOrNone(PyObject *x) : temp(0), orig(x), data(0) {
if (x && x != Py_None) {
if (PyUnicode_Check(x)) {
#if PY_MAJOR_VERSION > 2
this->data = PyUnicode_AsUTF8(x);
#else
this->temp = PyUnicode_AsUTF8String(x);
if (this->temp) this->data = PyBytes_AS_STRING(this->temp);
#endif
} else if (PyBytes_Check(x)) { this->data = PyBytes_AS_STRING(x); }
}
}
~StringOrNone() {
Py_CLEAR(this->temp);
Py_CLEAR(this->orig);
}
PyObject* get() { return this->orig; }
const char *c_str() { return this->data; }
explicit operator bool() { return this->orig ? true : false; }
};
class Serializer {
PyObject *buf = NULL;
size_t used = 0;
std::vector<std::string> nsmap;
bool
ensure_space(size_t amt) {
size_t required = amt + this->used;
if (!this->buf) {
this->buf = PyBytes_FromStringAndSize(NULL, std::max(required, static_cast<size_t>(128u * 1024u)));
if (!this->buf) return false;
return true;
}
if (required > static_cast<size_t>(PyBytes_GET_SIZE(this->buf))) {
if (_PyBytes_Resize(&(this->buf), std::max(
required, static_cast<size_t>(2 * PyBytes_GET_SIZE(this->buf)))) != 0) return false;
}
return true;
}
bool
write_data(const char *data, size_t sz) {
if (!this->ensure_space(sz)) return false;
memcpy(PyBytes_AS_STRING(this->buf) + this->used, data, sz);
this->used += sz;
return true;
}
bool
write_string_as_json(const char *str) {
const char *s = str;
if (!this->ensure_space(32)) return false;
char *b = PyBytes_AS_STRING(this->buf) + this->used;
*b++ = '"';
while (*s != 0) {
unsigned char c = *s++;
/* Encode the next character, and write it to b. */
switch (c) {
case '"':
*b++ = '\\';
*b++ = '"';
break;
case '\\':
*b++ = '\\';
*b++ = '\\';
break;
case '\b':
*b++ = '\\';
*b++ = 'b';
break;
case '\f':
*b++ = '\\';
*b++ = 'f';
break;
case '\n':
*b++ = '\\';
*b++ = 'n';
break;
case '\r':
*b++ = '\\';
*b++ = 'r';
break;
case '\t':
*b++ = '\\';
*b++ = 't';
break;
default: {
s--;
uint32_t unicode;
unsigned len = utf8_read_char(s, &unicode);
if (len == 0) s++;
else if (c < 0x1F) {
/* Encode using \u.... */
s += len;
if (unicode <= 0xFFFF) {
*b++ = '\\';
*b++ = 'u';
b += write_hex16(b, unicode);
} else {
/* Produce a surrogate pair. */
uint16_t uc, lc;
to_surrogate_pair(unicode, &uc, &lc);
*b++ = '\\';
*b++ = 'u';
b += write_hex16(b, uc);
*b++ = '\\';
*b++ = 'u';
b += write_hex16(b, lc);
}
} else {
/* Write the character directly. */
while (len-- > 0) *b++ = *s++;
}
break;
}
}
/*
* Update self to know about the new bytes,
* and set up b to write another encoded character.
*/
this->used = b - PyBytes_AS_STRING(this->buf);
if (!this->ensure_space(32)) return false;
b = PyBytes_AS_STRING(this->buf) + this->used;
}
*b++ = '"';
this->used = b - PyBytes_AS_STRING(this->buf);
return true;
}
inline int
namespace_index(const char *ns, size_t nslen) {
for (size_t i = 0; i < this->nsmap.size(); i++) {
if (namespaces_are_equal(this->nsmap[i].c_str(), ns, nslen)) return i;
}
this->nsmap.push_back(std::string(ns, nslen));
return this->nsmap.size() - 1;
}
bool
add_comment(const char *text, const char *tail, const char *type) {
if (!write_str_literal("{\"s\":")) return false;
if (!this->write_string_as_json(type)) return false;
if (text) {
if (!write_str_literal(",\"x\":")) return false;
if (!this->write_string_as_json(text)) return false;
}
if (tail) {
if (!write_str_literal(",\"l\":")) return false;
if (!this->write_string_as_json(tail)) return false;
}
if (!write_str_literal("}")) return false;
return true;
}
bool
write_attr(PyObject *args) {
const char *attr, *val;
#if PY_MAJOR_VERSION > 2
if (!PyArg_ParseTuple(args, "ss", &attr, &val)) return false;
#else
if (!PyArg_ParseTuple(args, "eses", "UTF-8", &attr, "UTF-8", &val)) return false;
#endif
const char *b = strrchr(attr, '}');
const char *attr_name = attr;
int nsindex = -1;
if (b) {
nsindex = this->namespace_index(attr + 1, b - attr - 1);
attr_name = b + 1;
}
if (!write_str_literal("[")) goto end;
if (!this->write_string_as_json(attr_name)) goto end;
if (!write_str_literal(",")) goto end;
if (!this->write_string_as_json(val)) goto end;
if (nsindex > -1) {
char buf[32];
this->write_data(buf, snprintf(buf, sizeof(buf), ",%d", nsindex));
}
if (!write_str_literal("]")) goto end;
end:
#if PY_MAJOR_VERSION < 3
PyMem_Free(attr); PyMem_Free(val);
#endif
return PyErr_Occurred() ? false : true;
}
bool
start_tag(const char *tag, const char *text, const char *tail, PyObject *items) {
if (!PyList_Check(items)) { PyErr_SetString(PyExc_TypeError, "attrs of a tag must be a list"); return false; }
Py_ssize_t num_attrs = PyList_Size(items);
const char *b = strrchr(tag, '}');
const char *tag_name = tag;
int nsindex = -1;
if (b) {
nsindex = this->namespace_index(tag + 1, b - tag - 1);
tag_name = b + 1;
}
if (!write_str_literal("{\"n\":")) return false;
if (!this->write_string_as_json(tag_name)) return false;
if (nsindex > 0) {
char buf[32];
this->write_data(buf, snprintf(buf, sizeof(buf), ",\"s\":%d", nsindex));
}
if (text) {
if (!write_str_literal(",\"x\":")) return false;
if (!this->write_string_as_json(text)) return false;
}
if (tail) {
if (!write_str_literal(",\"l\":")) return false;
if (!this->write_string_as_json(tail)) return false;
}
if (num_attrs > 0) {
if (!write_str_literal(",\"a\":[")) return false;
for (Py_ssize_t i = 0; i < num_attrs; i++) {
if (i) { if (!write_str_literal(",")) return false; }
if (!this->write_attr(PyList_GET_ITEM(items, i))) return false;
}
if (!write_str_literal("]")) return false;
}
return true;
}
bool
add_nsmap() {
if (!write_str_literal("[")) return false;
bool is_first = true;
for (auto x : this->nsmap) {
if (is_first) is_first = false;
else if (!write_str_literal(",")) return false;
if (!this->write_string_as_json(x.c_str())) return false;
}
if (!write_str_literal("]")) return false;
return true;
}
public:
Serializer() = default;
~Serializer() {
Py_CLEAR(this->buf);
}
PyObject*
serialize(PyObject *args) {
PyObject *root, *Comment;
if (!PyArg_ParseTuple(args, "OO", &root, &Comment)) return NULL;
std::stack<pyunique_ptr> stack;
std::vector<pyunique_ptr> children;
Py_INCREF(root);
stack.push(pyunique_ptr(root));
write_str_literal("{\"version\":1,\"tree\":");
while(!stack.empty()) {
pyunique_ptr e(std::move(stack.top()));
stack.pop();
PyObject *elem = e.get();
if (PyBytes_CheckExact(elem)) {
if (!this->write_data(PyBytes_AS_STRING(elem), PyBytes_GET_SIZE(elem))) return NULL;
continue;
}
StringOrNone tag(PyObject_GetAttrString(elem, "tag"));
StringOrNone text(PyObject_GetAttrString(elem, "text")), tail(PyObject_GetAttrString(elem, "tail"));
if (!tag || PyCallable_Check(tag.get())) {
const char *type = (tag && tag.get() == Comment) ? "c" : "o";
if (!this->add_comment(text.c_str(), tail.c_str(), type)) return NULL;
} else {
pyunique_ptr attrs(PyObject_CallMethod(elem, "items", NULL));
if (!attrs) return NULL;
if (!this->start_tag(tag.c_str(), text.c_str(), tail.c_str(), attrs.get())) return NULL;
pyunique_ptr iterator(PyObject_GetIter(elem));
if (!iterator) return NULL;
children.clear();
while(true) {
PyObject *child = PyIter_Next(iterator.get());
if (!child) { if (PyErr_Occurred()) return NULL; break; }
children.push_back(pyunique_ptr(child));
}
if (children.size() > 0) {
#define push_literal(x) { \
PyObject *lt = PyBytes_FromStringAndSize(x, sizeof(x) - 1); \
if (!lt) return NULL; \
stack.push(pyunique_ptr(lt));}
if (!write_str_literal(",\"c\":[")) return NULL;
push_literal("]}");
for (size_t i = children.size(); i-- > 0;) {
stack.push(std::move(children[i]));
if (i != 0) push_literal(",");
}
#undef push_literal
} else if (!write_str_literal("}")) return NULL;
}
}
if (!write_str_literal(",\"nsmap\":")) return NULL;
if (!this->add_nsmap()) return NULL;
if (!write_str_literal("}")) return NULL;
if (_PyBytes_Resize(&this->buf, this->used) != 0) return NULL;
PyObject *ans = this->buf;
this->buf = NULL;
this->used = 0;
this->nsmap.clear();
return ans;
}
};
static PyObject*
serialize(PyObject *self, PyObject *args) {
(void)self;
try {
Serializer s;
return s.serialize(args);
} catch(const std::exception & err) {
PyErr_Format(PyExc_ValueError, "An error occurred while trying to serialize to JSON: %s", err.what());
return NULL;
} catch (...) {
PyErr_SetString(PyExc_ValueError, "An unknown error occurred while trying to serialize to JSON");
return NULL;
}
}
// Boilerplate {{{
static char doc[] = "Serialize HTML as JSON efficiently";
static PyMethodDef methods[] = {
{"serialize", (PyCFunction)serialize, METH_VARARGS,
"Serialize the provided lxml tree to JSON"
},
{NULL} /* Sentinel */
};
#if PY_MAJOR_VERSION >= 3
#define INITERROR return NULL
#define INITMODULE PyModule_Create(&module)
static struct PyModuleDef module = {
/* m_base */ PyModuleDef_HEAD_INIT,
/* m_name */ "html_as_json",
/* m_doc */ doc,
/* m_size */ -1,
/* m_methods */ methods,
/* m_slots */ 0,
/* m_traverse */ 0,
/* m_clear */ 0,
/* m_free */ 0,
};
CALIBRE_MODINIT_FUNC PyInit_html_as_json(void) {
#else
#define INITERROR return
#define INITMODULE Py_InitModule3("html_as_json", methods, doc)
CALIBRE_MODINIT_FUNC inithtml_as_json(void) {
#endif
PyObject* m;
m = INITMODULE;
if (m == NULL) {
INITERROR;
}
#if PY_MAJOR_VERSION >= 3
return m;
#endif
}
// }}}