# Crow: include/crow/query_string.h Source File

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query_string.h
#pragma once
#include <stdio.h>
#include <string.h>
#include <string>
#include <vector>
#include <unordered_map>
#include <iostream>
#include <memory>
namespace crow
{
// ----------------------------------------------------------------------------
// qs_parse (modified)
// https://github.com/bartgrantham/qs_parse
// ----------------------------------------------------------------------------
/* Similar to strncmp, but handles URL-encoding for either string */
int qs_strncmp(const char* s, const char* qs, size_t n);
/* Finds the beginning of each key/value pair and stores a pointer in qs_kv.
* Also decodes the value portion of the k/v pair *in-place*. In a future
* enhancement it will also have a compile-time option of sorting qs_kv
* alphabetically by key. */
size_t qs_parse(char* qs, char* qs_kv[], size_t qs_kv_size, bool parse_url);
/* Used by qs_parse to decode the value portion of a k/v pair */
int qs_decode(char * qs);
/* Looks up the value according to the key on a pre-processed query string
* A future enhancement will be a compile-time option to look up the key
* in a pre-sorted qs_kv array via a binary search. */
//char * qs_k2v(const char * key, char * qs_kv[], int qs_kv_size);
char * qs_k2v(const char * key, char * const * qs_kv, size_t qs_kv_size, int nth);
/* Non-destructive lookup of value, based on key. User provides the
* destinaton string and length. */
char * qs_scanvalue(const char * key, const char * qs, char * val, size_t val_len);
// TODO: implement sorting of the qs_kv array; for now ensure it's not compiled
#undef _qsSORTING
// isxdigit _is_ available in <ctype.h>, but let's avoid another header instead
#define CROW_QS_ISHEX(x) ((((x)>='0'&&(x)<='9') || ((x)>='A'&&(x)<='F') || ((x)>='a'&&(x)<='f')) ? 1 : 0)
#define CROW_QS_HEX2DEC(x) (((x)>='0'&&(x)<='9') ? (x)-48 : ((x)>='A'&&(x)<='F') ? (x)-55 : ((x)>='a'&&(x)<='f') ? (x)-87 : 0)
#define CROW_QS_ISQSCHR(x) ((((x)=='=')||((x)=='#')||((x)=='&')||((x)=='\0')) ? 0 : 1)
inline int qs_strncmp(const char * s, const char * qs, size_t n)
{
unsigned char u1, u2, unyb, lnyb;
while(n-- > 0)
{
u1 = static_cast<unsigned char>(*s++);
u2 = static_cast<unsigned char>(*qs++);
if ( ! CROW_QS_ISQSCHR(u1) ) { u1 = '\0'; }
if ( ! CROW_QS_ISQSCHR(u2) ) { u2 = '\0'; }
if ( u1 == '+' ) { u1 = ' '; }
if ( u1 == '%' ) // easier/safer than scanf
{
unyb = static_cast<unsigned char>(*s++);
lnyb = static_cast<unsigned char>(*s++);
if ( CROW_QS_ISHEX(unyb) && CROW_QS_ISHEX(lnyb) )
u1 = (CROW_QS_HEX2DEC(unyb) * 16) + CROW_QS_HEX2DEC(lnyb);
else
u1 = '\0';
}
if ( u2 == '+' ) { u2 = ' '; }
if ( u2 == '%' ) // easier/safer than scanf
{
unyb = static_cast<unsigned char>(*qs++);
lnyb = static_cast<unsigned char>(*qs++);
if ( CROW_QS_ISHEX(unyb) && CROW_QS_ISHEX(lnyb) )
u2 = (CROW_QS_HEX2DEC(unyb) * 16) + CROW_QS_HEX2DEC(lnyb);
else
u2 = '\0';
}
if ( u1 != u2 )
return u1 - u2;
if ( u1 == '\0' )
return 0;
}
if ( CROW_QS_ISQSCHR(*qs) )
return -1;
else
return 0;
}
inline size_t qs_parse(char* qs, char* qs_kv[], size_t qs_kv_size, bool parse_url = true)
{
size_t i, j;
char * substr_ptr;
for(i=0; i<qs_kv_size; i++) qs_kv[i] = NULL;
// find the beginning of the k/v substrings or the fragment
substr_ptr = parse_url ? qs + strcspn(qs, "?#") : qs;
if (parse_url)
{
if (substr_ptr[0] != '\0')
substr_ptr++;
else
return 0; // no query or fragment
}
i=0;
while(i<qs_kv_size)
{
qs_kv[i] = substr_ptr;
j = strcspn(substr_ptr, "&");
if ( substr_ptr[j] == '\0' ) { i++; break; } // x &'s -> means x iterations of this loop -> means *x+1* k/v pairs
substr_ptr += j + 1;
i++;
}
// we only decode the values in place, the keys could have '='s in them
// which will hose our ability to distinguish keys from values later
for(j=0; j<i; j++)
{
substr_ptr = qs_kv[j] + strcspn(qs_kv[j], "=&#");
if ( substr_ptr[0] == '&' || substr_ptr[0] == '\0') // blank value: skip decoding
substr_ptr[0] = '\0';
else
qs_decode(++substr_ptr);
}
#ifdef _qsSORTING
// TODO: qsort qs_kv, using qs_strncmp() for the comparison
#endif
return i;
}
inline int qs_decode(char * qs)
{
int i=0, j=0;
while( CROW_QS_ISQSCHR(qs[j]) )
{
if ( qs[j] == '+' ) { qs[i] = ' '; }
else if ( qs[j] == '%' ) // easier/safer than scanf
{
if ( ! CROW_QS_ISHEX(qs[j+1]) || ! CROW_QS_ISHEX(qs[j+2]) )
{
qs[i] = '\0';
return i;
}
qs[i] = (CROW_QS_HEX2DEC(qs[j+1]) * 16) + CROW_QS_HEX2DEC(qs[j+2]);
j+=2;
}
else
{
qs[i] = qs[j];
}
i++; j++;
}
qs[i] = '\0';
return i;
}
inline char * qs_k2v(const char * key, char * const * qs_kv, size_t qs_kv_size, int nth = 0)
{
size_t i;
size_t key_len, skip;
key_len = strlen(key);
#ifdef _qsSORTING
// TODO: binary search for key in the sorted qs_kv
#else // _qsSORTING
for(i=0; i<qs_kv_size; i++)
{
// we rely on the unambiguous '=' to find the value in our k/v pair
if ( qs_strncmp(key, qs_kv[i], key_len) == 0 )
{
skip = strcspn(qs_kv[i], "=");
if ( qs_kv[i][skip] == '=' )
skip++;
// return (zero-char value) ? ptr to trailing '\0' : ptr to value
if(nth == 0)
return qs_kv[i] + skip;
else
--nth;
}
}
#endif // _qsSORTING
return nullptr;
}
inline std::unique_ptr<std::pair<std::string, std::string>> qs_dict_name2kv(const char * dict_name, char * const * qs_kv, size_t qs_kv_size, int nth = 0)
{
size_t i;
size_t name_len, skip_to_eq, skip_to_brace_open, skip_to_brace_close;
name_len = strlen(dict_name);
#ifdef _qsSORTING
// TODO: binary search for key in the sorted qs_kv
#else // _qsSORTING
for(i=0; i<qs_kv_size; i++)
{
if ( strncmp(dict_name, qs_kv[i], name_len) == 0 )
{
skip_to_eq = strcspn(qs_kv[i], "=");
if ( qs_kv[i][skip_to_eq] == '=' )
skip_to_eq++;
skip_to_brace_open = strcspn(qs_kv[i], "[");
if ( qs_kv[i][skip_to_brace_open] == '[' )
skip_to_brace_open++;
skip_to_brace_close = strcspn(qs_kv[i], "]");
if ( skip_to_brace_open <= skip_to_brace_close &&
skip_to_brace_open > 0 &&
skip_to_brace_close > 0 &&
nth == 0 )
{
auto key = std::string(qs_kv[i] + skip_to_brace_open, skip_to_brace_close - skip_to_brace_open);
auto value = std::string(qs_kv[i] + skip_to_eq);
return std::unique_ptr<std::pair<std::string, std::string>>(new std::pair<std::string, std::string>(key, value));
}
else
{
--nth;
}
}
}
#endif // _qsSORTING
return nullptr;
}
inline char * qs_scanvalue(const char * key, const char * qs, char * val, size_t val_len)
{
size_t i, key_len;
const char * tmp;
// find the beginning of the k/v substrings
if ( (tmp = strchr(qs, '?')) != NULL )
qs = tmp + 1;
key_len = strlen(key);
while(qs[0] != '#' && qs[0] != '\0')
{
if ( qs_strncmp(key, qs, key_len) == 0 )
break;
qs += strcspn(qs, "&") + 1;
}
if ( qs[0] == '\0' ) return NULL;
qs += strcspn(qs, "=&#");
if ( qs[0] == '=' )
{
qs++;
i = strcspn(qs, "&=#");
#ifdef _MSC_VER
strncpy_s(val, val_len, qs, (val_len - 1)<(i + 1) ? (val_len - 1) : (i + 1));
#else
strncpy(val, qs, (val_len - 1)<(i + 1) ? (val_len - 1) : (i + 1));
#endif
qs_decode(val);
}
else
{
if ( val_len > 0 )
val[0] = '\0';
}
return val;
}
}
// ----------------------------------------------------------------------------
namespace crow
{
struct request;
/// A class to represent any data coming after the `?` in the request URL into key-value pairs.
class query_string
{
public:
static const int MAX_KEY_VALUE_PAIRS_COUNT = 256;
query_string() = default;
query_string(const query_string& qs):
url_(qs.url_)
{
for (auto p : qs.key_value_pairs_)
{
key_value_pairs_.push_back((char*)(p - qs.url_.c_str() + url_.c_str()));
}
}
query_string& operator=(const query_string& qs)
{
url_ = qs.url_;
key_value_pairs_.clear();
for (auto p : qs.key_value_pairs_)
{
key_value_pairs_.push_back((char*)(p - qs.url_.c_str() + url_.c_str()));
}
return *this;
}
query_string& operator=(query_string&& qs) noexcept
{
key_value_pairs_ = std::move(qs.key_value_pairs_);
char* old_data = (char*)qs.url_.c_str();
url_ = std::move(qs.url_);
for (auto& p : key_value_pairs_)
{
p += (char*)url_.c_str() - old_data;
}
return *this;
}
query_string(std::string params, bool url = true):
url_(std::move(params))
{
if (url_.empty())
return;
key_value_pairs_.resize(MAX_KEY_VALUE_PAIRS_COUNT);
size_t count = qs_parse(&url_[0], &key_value_pairs_[0], MAX_KEY_VALUE_PAIRS_COUNT, url);
key_value_pairs_.resize(count);
key_value_pairs_.shrink_to_fit();
}
void clear()
{
key_value_pairs_.clear();
url_.clear();
}
friend std::ostream& operator<<(std::ostream& os, const query_string& qs)
{
os << "[ ";
for (size_t i = 0; i < qs.key_value_pairs_.size(); ++i)
{
if (i)
os << ", ";
os << qs.key_value_pairs_[i];
}
os << " ]";
return os;
}
/// Get a value from a name, used for `?name=value`.
///
/// Note: this method returns the value of the first occurrence of the key only, to return all occurrences, see \ref get_list().
char* get(const std::string& name) const
{
char* ret = qs_k2v(name.c_str(), key_value_pairs_.data(), key_value_pairs_.size());
return ret;
}
/// Works similar to \ref get() except it removes the item from the query string.
char* pop(const std::string& name)
{
char* ret = get(name);
if (ret != nullptr)
{
for (unsigned int i = 0; i < key_value_pairs_.size(); i++)
{
std::string str_item(key_value_pairs_[i]);
if (str_item.substr(0, name.size() + 1) == name + '=')
{
key_value_pairs_.erase(key_value_pairs_.begin() + i);
break;
}
}
}
return ret;
}
/// Returns a list of values, passed as `?name[]=value1&name[]=value2&...name[]=valuen` with n being the size of the list.
///
/// Note: Square brackets in the above example are controlled by `use_brackets` boolean (true by default). If set to false, the example becomes `?name=value1,name=value2...name=valuen`
std::vector<char*> get_list(const std::string& name, bool use_brackets = true) const
{
std::vector<char*> ret;
std::string plus = name + (use_brackets ? "[]" : "");
char* element = nullptr;
int count = 0;
while (1)
{
element = qs_k2v(plus.c_str(), key_value_pairs_.data(), key_value_pairs_.size(), count++);
if (!element)
break;
ret.push_back(element);
}
return ret;
}
/// Similar to \ref get_list() but it removes the
std::vector<char*> pop_list(const std::string& name, bool use_brackets = true)
{
std::vector<char*> ret = get_list(name, use_brackets);
if (!ret.empty())
{
for (unsigned int i = 0; i < key_value_pairs_.size(); i++)
{
std::string str_item(key_value_pairs_[i]);
if ((use_brackets ? (str_item.substr(0, name.size() + 3) == name + "[]=") : (str_item.substr(0, name.size() + 1) == name + '=')))
{
key_value_pairs_.erase(key_value_pairs_.begin() + i--);
}
}
}
return ret;
}
/// Works similar to \ref get_list() except the brackets are mandatory must not be empty.
///
/// For example calling `get_dict(yourname)` on `?yourname[sub1]=42&yourname[sub2]=84` would give a map containing `{sub1 : 42, sub2 : 84}`.
///
/// if your query string has both empty brackets and ones with a key inside, use pop_list() to get all the values without a key before running this method.
std::unordered_map<std::string, std::string> get_dict(const std::string& name) const
{
std::unordered_map<std::string, std::string> ret;
int count = 0;
while (1)
{
if (auto element = qs_dict_name2kv(name.c_str(), key_value_pairs_.data(), key_value_pairs_.size(), count++))
ret.insert(*element);
else
break;
}
return ret;
}
/// Works the same as \ref get_dict() but removes the values from the query string.
std::unordered_map<std::string, std::string> pop_dict(const std::string& name)
{
std::unordered_map<std::string, std::string> ret = get_dict(name);
if (!ret.empty())
{
for (unsigned int i = 0; i < key_value_pairs_.size(); i++)
{
std::string str_item(key_value_pairs_[i]);
if (str_item.substr(0, name.size() + 1) == name + '[')
{
key_value_pairs_.erase(key_value_pairs_.begin() + i--);
}
}
}
return ret;
}
std::vector<std::string> keys() const
{
std::vector<std::string> keys;
keys.reserve(key_value_pairs_.size());
for (const char* const element : key_value_pairs_)
{
const char* delimiter = strchr(element, '=');
if (delimiter)
keys.emplace_back(element, delimiter);
else
keys.emplace_back(element);
}
return keys;
}
private:
std::string url_;
std::vector<char*> key_value_pairs_;
};
} // namespace crow
crow::query_string
A class to represent any data coming after the ? in the request URL into key-value pairs.
Definition query_string.h:294
crow::query_string::pop_dict
std::unordered_map< std::string, std::string > pop_dict(const std::string &name)
Works the same as get_dict() but removes the values from the query string.
Definition query_string.h:455
crow::query_string::pop
char * pop(const std::string &name)
Works similar to get() except it removes the item from the query string.
Definition query_string.h:376
crow::query_string::get_dict
std::unordered_map< std::string, std::string > get_dict(const std::string &name) const
Works similar to get_list() except the brackets are mandatory must not be empty.
Definition query_string.h:439
crow::query_string::get_list
std::vector< char * > get_list(const std::string &name, bool use_brackets=true) const
Returns a list of values, passed as ?name[]=value1&name[]=value2&...name[]=valuen with n being the si...
Definition query_string.h:398
crow::query_string::pop_list
std::vector< char * > pop_list(const std::string &name, bool use_brackets=true)
Similar to get_list() but it removes the.
Definition query_string.h:416
crow::query_string::get
char * get(const std::string &name) const
Get a value from a name, used for ?name=value.
Definition query_string.h:369
crow
The main namespace of the library. In this namespace is defined the most important classes and functi...