Vendor import of llvm trunk r154661:

http://llvm.org/svn/llvm-project/llvm/trunk@r154661

1 files changed, 448 insertions, 0 deletions

diff --git a/include/llvm/Support/JSONParser.h b/include/llvm/Support/JSONParser.h
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+//===--- 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_SUPPORT_JSON_PARSER_H
+#define LLVM_SUPPORT_JSON_PARSER_H
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/SourceMgr.h"
+
+namespace llvm {
+
+class JSONContainer;
+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:
+  Kind MyKind;
+};
+
+/// \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, SourceMgr *SM);
+
+  /// \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 iterate over the
+  /// returned object 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;
+
+private:
+  /// \brief These methods manage the implementation details of parsing new JSON
+  /// atoms.
+  /// @{
+  JSONString *parseString();
+  JSONValue *parseValue();
+  JSONKeyValuePair *parseKeyValuePair();
+  /// @}
+
+  /// \brief Helpers to parse the elements out of both forms of containers.
+  /// @{
+  const JSONAtom *parseElement(JSONAtom::Kind ContainerKind);
+  StringRef::iterator parseFirstElement(JSONAtom::Kind ContainerKind,
+                                        char StartChar, char EndChar,
+                                        const JSONAtom *&Element);
+  StringRef::iterator parseNextElement(JSONAtom::Kind ContainerKind,
+                                       char EndChar,
+                                       const JSONAtom *&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);
+  /// }
+
+  /// \brief Skips all elements in the given container.
+  bool skipContainer(const JSONContainer &Container);
+
+  /// \brief Skips to the next position behind the given JSON atom.
+  bool skip(const JSONAtom &Atom);
+
+  /// 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.
+  MemoryBuffer *InputBuffer;
+
+  /// \brief The source manager used for diagnostics and buffer management.
+  SourceMgr *SM;
+
+  /// \brief The current position in the parse stream.
+  StringRef::iterator Position;
+
+  /// \brief The end position for fast EOF checks without introducing
+  /// unnecessary dereferences.
+  StringRef::iterator End;
+
+  /// \brief If true, an error has occurred.
+  bool Failed;
+
+  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) {}
+
+  StringRef RawText;
+
+  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) {}
+
+  friend class JSONParser;
+
+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.
+class JSONContainer : public JSONValue {
+private:
+  /// \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 AtomIterator {
+  public:
+    AtomIterator(const AtomIterator &I) : Container(I.Container) {}
+
+    /// \brief Iterator interface.
+    ///@{
+    bool operator==(const AtomIterator &I) const {
+      if (isEnd() || I.isEnd())
+        return isEnd() == I.isEnd();
+      return Container->Position == I.Container->Position;
+    }
+    bool operator!=(const AtomIterator &I) const {
+      return !(*this == I);
+    }
+    AtomIterator &operator++() {
+      Container->parseNextElement();
+      return *this;
+    }
+    const JSONAtom *operator*() {
+      return Container->Current;
+    }
+    ///@}
+
+  private:
+    /// \brief Create an iterator for which 'isEnd' returns true.
+    AtomIterator() : Container(0) {}
+
+    /// \brief Create an iterator for the given container.
+    AtomIterator(const JSONContainer *Container) : Container(Container) {}
+
+    bool isEnd() const {
+      return Container == 0 || Container->Position == StringRef::iterator();
+    }
+
+    const JSONContainer * const Container;
+
+    friend class JSONContainer;
+  };
+
+protected:
+  /// \brief An iterator for the specified AtomT.
+  ///
+  /// Used for the implementation of iterators for JSONArray and JSONObject.
+  template <typename AtomT>
+  class IteratorTemplate : public std::iterator<std::forward_iterator_tag,
+                                                const AtomT*> {
+  public:
+    explicit IteratorTemplate(const AtomIterator& AtomI)
+      : AtomI(AtomI) {}
+
+    bool operator==(const IteratorTemplate &I) const {
+      return AtomI == I.AtomI;
+    }
+    bool operator!=(const IteratorTemplate &I) const { return !(*this == I); }
+
+    IteratorTemplate &operator++() {
+      ++AtomI;
+      return *this;
+    }
+
+    const AtomT *operator*() { return dyn_cast<AtomT>(*AtomI); }
+
+  private:
+    AtomIterator AtomI;
+  };
+
+  JSONContainer(JSONParser *Parser, char StartChar, char EndChar,
+                JSONAtom::Kind ContainerKind)
+    : JSONValue(ContainerKind), Parser(Parser),
+      Position(), Current(0), Started(false),
+      StartChar(StartChar), EndChar(EndChar) {}
+
+  /// \brief Returns a lazy parsing iterator over the container.
+  ///
+  /// As the iterator drives the parse stream, begin() must only be called
+  /// once per container.
+  AtomIterator atom_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(getKind(), StartChar, EndChar, Current);
+    return AtomIterator(this);
+  }
+  AtomIterator atom_end() const {
+    return AtomIterator();
+  }
+
+private:
+  AtomIterator atom_current() const {
+    if (!Started)
+      return atom_begin();
+
+    return AtomIterator(this);
+  }
+
+  /// \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 {
+    Parser->skip(*Current);
+    Position = Parser->parseNextElement(getKind(), 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 JSONAtom *Current;
+  mutable bool Started;
+
+  const char StartChar;
+  const char EndChar;
+
+  friend class JSONParser;
+
+public:
+  /// \brief dyn_cast helpers
+  ///@{
+  static bool classof(const JSONAtom *Atom) {
+    switch (Atom->getKind()) {
+      case JK_Array:
+      case JK_Object:
+        return true;
+      case JK_KeyValuePair:
+      case JK_String:
+        return false;
+    }
+    llvm_unreachable("Invalid JSONAtom kind");
+  }
+  static bool classof(const JSONContainer *Container) { return true; }
+  ///@}
+};
+
+/// \brief A simple JSON array.
+class JSONArray : public JSONContainer {
+public:
+  typedef IteratorTemplate<JSONValue> const_iterator;
+
+  /// \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 { return const_iterator(atom_begin()); }
+  const_iterator end() const { return const_iterator(atom_end()); }
+
+private:
+  JSONArray(JSONParser *Parser)
+    : JSONContainer(Parser, '[', ']', JSONAtom::JK_Array) {}
+
+public:
+  /// \brief dyn_cast helpers
+  ///@{
+  static bool classof(const JSONAtom *Atom) {
+    return Atom->getKind() == JSONAtom::JK_Array;
+  }
+  static bool classof(const JSONArray *Array) { return true; }
+  ///@}
+
+  friend class JSONParser;
+};
+
+/// \brief A JSON object: an iterable list of JSON key-value pairs.
+class JSONObject : public JSONContainer {
+public:
+  typedef IteratorTemplate<JSONKeyValuePair> const_iterator;
+
+  /// \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 { return const_iterator(atom_begin()); }
+  const_iterator end() const { return const_iterator(atom_end()); }
+
+private:
+  JSONObject(JSONParser *Parser)
+    : JSONContainer(Parser, '{', '}', JSONAtom::JK_Object) {}
+
+public:
+  /// \brief dyn_cast helpers
+  ///@{
+  static bool classof(const JSONAtom *Atom) {
+    return Atom->getKind() == JSONAtom::JK_Object;
+  }
+  static bool classof(const JSONObject *Object) { return true; }
+  ///@}
+
+  friend class JSONParser;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_SUPPORT_JSON_PARSER_H