6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-06-22 10:24:26 +00:00
Code Issues Projects Releases Wiki Activity

Adds a JSON parser and a benchmark (json-bench) to catch performance regressions.

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146735 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Manuel Klimek
2011-12-16 13:09:10 +00:00
parent db21f4c187
commit 76f13017fc
12 changed files with 996 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

444
include/llvm/Support/JSONParser.h Normal file
View File

@ -0,0 +1,444 @@
//===--- JsonParser.h - Simple JSON parser ----------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements a JSON parser.
//
// See http://www.json.org/ for an overview.
// See http://www.ietf.org/rfc/rfc4627.txt for the full standard.
//
// FIXME: Currently this supports a subset of JSON. Specifically, support
// for numbers, booleans and null for values is missing.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_TOOLING_JSON_PARSER_H
#define LLVM_CLANG_TOOLING_JSON_PARSER_H
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/ErrorHandling.h"
#include <string>
namespace llvm {
class JSONString;
class JSONValue;
class JSONKeyValuePair;
/// \brief Base class for a parsable JSON atom.
///
/// This class has no semantics other than being a unit of JSON data which can
/// be parsed out of a JSON document.
class JSONAtom {
public:
/// \brief Possible types of JSON objects.
enum Kind { JK_KeyValuePair, JK_Array, JK_Object, JK_String };
/// \brief Returns the type of this value.
Kind getKind() const { return MyKind; }
static bool classof(const JSONAtom *Atom) { return true; }
protected:
JSONAtom(Kind MyKind) : MyKind(MyKind) {}
private:
/// \brief Parses to the end of the object and returns whether parsing
/// was successful.
bool skip() const;
Kind MyKind;
friend class JSONParser;
friend class JSONKeyValuePair;
template <typename, char, char, JSONAtom::Kind> friend class JSONContainer;
};
/// \brief A parser for JSON text.
///
/// Use an object of JSONParser to iterate over the values of a JSON text.
/// All objects are parsed during the iteration, so you can only iterate once
/// over the JSON text, but the cost of partial iteration is minimized.
/// Create a new JSONParser if you want to iterate multiple times.
class JSONParser {
public:
/// \brief Create a JSONParser for the given input.
///
/// Parsing is started via parseRoot(). Access to the object returned from
/// parseRoot() will parse the input lazily.
JSONParser(StringRef Input);
/// \brief Returns the outermost JSON value (either an array or an object).
///
/// Can return NULL if the input does not start with an array or an object.
/// The object is not parsed yet - the caller must either iterate over the
/// returned object or call 'skip' to trigger parsing.
///
/// A JSONValue can be either a JSONString, JSONObject or JSONArray.
JSONValue *parseRoot();
/// \brief Parses the JSON text and returns whether it is valid JSON.
///
/// In case validate() return false, failed() will return true and
/// getErrorMessage() will return the parsing error.
bool validate();
/// \brief Returns true if an error occurs during parsing.
///
/// If there was an error while parsing an object that was created by
/// iterating over the result of 'parseRoot', 'failed' will return true.
bool failed() const;
/// \brief Returns an error message when 'failed' returns true.
std::string getErrorMessage() const;
private:
/// \brief These methods manage the implementation details of parsing new JSON
/// atoms.
/// @{
JSONString *parseString();
JSONValue *parseValue();
JSONKeyValuePair *parseKeyValuePair();
/// @}
/// \brief Templated helpers to parse the elements out of both forms of JSON
/// containers.
/// @{
template <typename AtomT> AtomT *parseElement();
template <typename AtomT, char StartChar, char EndChar>
StringRef::iterator parseFirstElement(const AtomT *&Element);
template <typename AtomT, char EndChar>
StringRef::iterator parseNextElement(const AtomT *&Element);
/// @}
/// \brief Whitespace parsing.
/// @{
void nextNonWhitespace();
bool isWhitespace();
/// @}
/// \brief These methods are used for error handling.
/// {
void setExpectedError(StringRef Expected, StringRef Found);
void setExpectedError(StringRef Expected, char Found);
bool errorIfAtEndOfFile(StringRef Message);
bool errorIfNotAt(char C, StringRef Message);
/// }
/// All nodes are allocated by the parser and will be deallocated when the
/// parser is destroyed.
BumpPtrAllocator ValueAllocator;
/// \brief The original input to the parser.
const StringRef Input;
/// \brief The current position in the parse stream.
StringRef::iterator Position;
/// \brief If non-empty, an error has occurred.
std::string ErrorMessage;
template <typename AtomT, char StartChar, char EndChar,
JSONAtom::Kind ContainerKind>
friend class JSONContainer;
};
/// \brief Base class for JSON value objects.
///
/// This object represents an abstract JSON value. It is the root node behind
/// the group of JSON entities that can represent top-level values in a JSON
/// document. It has no API, and is just a placeholder in the type hierarchy of
/// nodes.
class JSONValue : public JSONAtom {
protected:
JSONValue(Kind MyKind) : JSONAtom(MyKind) {}
public:
/// \brief dyn_cast helpers
///@{
static bool classof(const JSONAtom *Atom) {
switch (Atom->getKind()) {
case JK_Array:
case JK_Object:
case JK_String:
return true;
case JK_KeyValuePair:
return false;
};
llvm_unreachable("Invalid JSONAtom kind");
}
static bool classof(const JSONValue *Value) { return true; }
///@}
};
/// \brief Gives access to the text of a JSON string.
///
/// FIXME: Implement a method to return the unescaped text.
class JSONString : public JSONValue {
public:
/// \brief Returns the underlying parsed text of the string.
///
/// This is the unescaped content of the JSON text.
/// See http://www.ietf.org/rfc/rfc4627.txt for details.
StringRef getRawText() const { return RawText; };
private:
JSONString(StringRef RawText) : JSONValue(JK_String), RawText(RawText) {}
/// \brief Skips to the next position in the parse stream.
bool skip() const { return true; };
StringRef RawText;
friend class JSONAtom;
friend class JSONParser;
public:
/// \brief dyn_cast helpers
///@{
static bool classof(const JSONAtom *Atom) {
return Atom->getKind() == JK_String;
}
static bool classof(const JSONString *String) { return true; }
///@}
};
/// \brief A (key, value) tuple of type (JSONString *, JSONValue *).
///
/// Note that JSONKeyValuePair is not a JSONValue, it is a bare JSONAtom.
/// JSONKeyValuePairs can be elements of a JSONObject, but not of a JSONArray.
/// They are not viable as top-level values either.
class JSONKeyValuePair : public JSONAtom {
public:
const JSONString * const Key;
const JSONValue * const Value;
private:
JSONKeyValuePair(const JSONString *Key, const JSONValue *Value)
: JSONAtom(JK_KeyValuePair), Key(Key), Value(Value) {}
/// \brief Skips to the next position in the parse stream.
bool skip() const { return Value->skip(); };
friend class JSONAtom;
friend class JSONParser;
template <typename, char, char, JSONAtom::Kind> friend class JSONContainer;
public:
/// \brief dyn_cast helpers
///@{
static bool classof(const JSONAtom *Atom) {
return Atom->getKind() == JK_KeyValuePair;
}
static bool classof(const JSONKeyValuePair *KeyValuePair) { return true; }
///@}
};
/// \brief Implementation of JSON containers (arrays and objects).
///
/// JSONContainers drive the lazy parsing of JSON arrays and objects via
/// forward iterators. Call 'skip' to validate parsing of all elements of the
/// container and to position the parse stream behind the container.
template <typename AtomT, char StartChar, char EndChar,
JSONAtom::Kind ContainerKind>
class JSONContainer : public JSONValue {
public:
/// \brief An iterator that parses the underlying container during iteration.
///
/// Iterators on the same collection use shared state, so when multiple copies
/// of an iterator exist, only one is allowed to be used for iteration;
/// iterating multiple copies of an iterator of the same collection will lead
/// to undefined behavior.
class const_iterator : public std::iterator<std::forward_iterator_tag,
const AtomT*> {
public:
const_iterator(const const_iterator &I) : Container(I.Container) {}
bool operator==(const const_iterator &I) const {
if (isEnd() || I.isEnd())
return isEnd() == I.isEnd();
return Container->Position == I.Container->Position;
}
bool operator!=(const const_iterator &I) const { return !(*this == I); }
const_iterator &operator++() {
Container->parseNextElement();
return *this;
}
const AtomT *operator*() { return Container->Current; }
private:
/// \brief Create an iterator for which 'isEnd' returns true.
const_iterator() : Container(0) {}
/// \brief Create an iterator for the given container.
const_iterator(const JSONContainer *Container) : Container(Container) {}
bool isEnd() const {
return Container == 0 || Container->Position == StringRef::iterator();
}
const JSONContainer * const Container;
friend class JSONContainer;
};
/// \brief Returns a lazy parsing iterator over the container.
///
/// As the iterator drives the parse stream, begin() must only be called
/// once per container.
const_iterator begin() const {
if (Started)
report_fatal_error("Cannot parse container twice.");
Started = true;
// Set up the position and current element when we begin iterating over the
// container.
Position = Parser->parseFirstElement<AtomT, StartChar, EndChar>(Current);
return const_iterator(this);
}
const_iterator end() const {
return const_iterator();
}
private:
JSONContainer(JSONParser *Parser)
: JSONValue(ContainerKind), Parser(Parser),
Position(), Current(0), Started(false) {}
const_iterator current() const {
if (!Started)
return begin();
return const_iterator(this);
}
/// \brief Skips to the next position in the parse stream.
bool skip() const {
for (const_iterator I = current(), E = end(); I != E; ++I) {
assert(*I != 0);
if (!(*I)->skip())
return false;
}
return !Parser->failed();
}
/// \brief Parse the next element in the container into the Current element.
///
/// This routine is called as an iterator into this container walks through
/// its elements. It mutates the container's internal current node to point to
/// the next atom of the container.
void parseNextElement() const {
Current->skip();
Position = Parser->parseNextElement<AtomT, EndChar>(Current);
}
// For parsing, JSONContainers call back into the JSONParser.
JSONParser * const Parser;
// 'Position', 'Current' and 'Started' store the state of the parse stream
// for iterators on the container, they don't change the container's elements
// and are thus marked as mutable.
mutable StringRef::iterator Position;
mutable const AtomT *Current;
mutable bool Started;
friend class JSONAtom;
friend class JSONParser;
friend class const_iterator;
public:
/// \brief dyn_cast helpers
///@{
static bool classof(const JSONAtom *Atom) {
return Atom->getKind() == ContainerKind;
}
static bool classof(const JSONContainer *Container) { return true; }
///@}
};
/// \brief A simple JSON array.
typedef JSONContainer<JSONValue, '[', ']', JSONAtom::JK_Array> JSONArray;
/// \brief A JSON object: an iterable list of JSON key-value pairs.
typedef JSONContainer<JSONKeyValuePair, '{', '}', JSONAtom::JK_Object>
JSONObject;
/// \brief Template adaptor to dispatch element parsing for values.
template <> JSONValue *JSONParser::parseElement();
/// \brief Template adaptor to dispatch element parsing for key value pairs.
template <> JSONKeyValuePair *JSONParser::parseElement();
/// \brief Parses the first element of a JSON array or object, or closes the
/// array.
///
/// The method assumes that the current position is before the first character
/// of the element, with possible white space in between. When successful, it
/// returns the new position after parsing the element. Otherwise, if there is
/// no next value, it returns a default constructed StringRef::iterator.
template <typename AtomT, char StartChar, char EndChar>
StringRef::iterator JSONParser::parseFirstElement(const AtomT *&Element) {
assert(*Position == StartChar);
Element = 0;
nextNonWhitespace();
if (errorIfAtEndOfFile("value or end of container at start of container"))
return StringRef::iterator();
if (*Position == EndChar)
return StringRef::iterator();
Element = parseElement<AtomT>();
if (Element == 0)
return StringRef::iterator();
return Position;
}
/// \brief Parses the next element of a JSON array or object, or closes the
/// array.
///
/// The method assumes that the current position is before the ',' which
/// separates the next element from the current element. When successful, it
/// returns the new position after parsing the element. Otherwise, if there is
/// no next value, it returns a default constructed StringRef::iterator.
template <typename AtomT, char EndChar>
StringRef::iterator JSONParser::parseNextElement(const AtomT *&Element) {
Element = 0;
nextNonWhitespace();
if (errorIfAtEndOfFile("',' or end of container for next element"))
return 0;
switch (*Position) {
case ',':
nextNonWhitespace();
if (errorIfAtEndOfFile("element in container"))
return StringRef::iterator();
Element = parseElement<AtomT>();
if (Element == 0)
return StringRef::iterator();
return Position;
case EndChar:
return StringRef::iterator();
default:
setExpectedError("',' or end of container for next element", *Position);
return StringRef::iterator();
}
}
} // end namespace llvm
#endif // LLVM_CLANG_TOOLING_JSON_PARSER_H