138 lines
4.4 KiB
C++
138 lines
4.4 KiB
C++
/* -*- C++ -*-
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* Serene Programming Language
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*
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* Copyright (c) 2019-2022 Sameer Rahmani <lxsameer@gnu.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* Commentary:
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* `Reader` is the base parser class and accepts a buffer like objenct (usually
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* `llvm::StringRef`) as the input and parsess it to create an AST (look at the
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* `serene::exprs::Expression` class).
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*
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* The parsing algorithm is quite simple and it is a LL(2). It means that, we
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* start parsing the input from the very first character and parse the input
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* one char at a time till we reach the end of the input. Please note that
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* when we call the `advance` function to move forward in the buffer, we
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* can't go back. In order to look ahead in the buffer without moving in the
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* buffer we use the `nextChar` method.
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*
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* We have dedicated methods to read different forms like `list`, `symbol`
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* `number` and etc. Each of them return a `MaybeNode` that in the success
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* case contains the node and an `Error` on the failure case.
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*/
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#ifndef SERENE_READER_READER_H
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#define SERENE_READER_READER_H
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#include "serene/errors.h"
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#include "serene/exprs/expression.h"
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#include "serene/exprs/list.h"
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#include "serene/exprs/symbol.h"
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#include "serene/reader/location.h"
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#include "serene/serene.h"
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#include <serene/export.h>
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#include <system_error>
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#include <llvm/Support/Debug.h>
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#include <llvm/Support/MemoryBuffer.h>
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#include <llvm/Support/MemoryBufferRef.h>
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#include <llvm/Support/raw_ostream.h>
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#include <memory>
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#include <sstream>
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#include <stdexcept>
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#include <string>
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#include <vector>
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#define READER_LOG(...) \
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DEBUG_WITH_TYPE("READER", llvm::dbgs() \
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<< "[READER]: " << __VA_ARGS__ << "\n");
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namespace serene::reader {
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/// Base reader class which reads from a string directly.
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class Reader {
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private:
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SereneContext &ctx;
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llvm::StringRef ns;
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llvm::Optional<llvm::StringRef> filename;
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const char *currentChar = NULL;
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llvm::StringRef buf;
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/// The position tracker that we will use to determine the end of the
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/// buffer since the buffer might not be null terminated
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size_t currentPos = -1;
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Location currentLocation;
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bool readEOL = false;
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/// Returns a clone of the current location
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Location getCurrentLocation();
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/// Returns the next character from the stream.
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/// @param skip_whitespace An indicator to whether skip white space like chars
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/// or not
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void advance(bool skipWhitespace = false);
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void advanceByOne();
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const char *nextChar(bool skipWhitespace = false, unsigned count = 1);
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/// Returns a boolean indicating whether the given input character is valid
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/// for an identifier or not.
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static bool isValidForIdentifier(char c);
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// The property to store the ast tree
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exprs::Ast ast;
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exprs::MaybeNode readSymbol();
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exprs::MaybeNode readNumber(bool);
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exprs::MaybeNode readList();
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exprs::MaybeNode readExpr();
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bool isEndOfBuffer(const char *);
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public:
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Reader(SereneContext &ctx, llvm::StringRef buf, llvm::StringRef ns,
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llvm::Optional<llvm::StringRef> filename);
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Reader(SereneContext &ctx, llvm::MemoryBufferRef buf, llvm::StringRef ns,
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llvm::Optional<llvm::StringRef> filename);
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// void setInput(const llvm::StringRef string);
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/// Parses the the input and creates a possible AST out of it or errors
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/// otherwise.
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exprs::MaybeAst read();
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~Reader();
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};
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/// Parses the given `input` string and returns a `Result<ast>`
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/// which may contains an AST or an `llvm::Error`
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SERENE_EXPORT exprs::MaybeAst read(SereneContext &ctx, llvm::StringRef input,
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llvm::StringRef ns,
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llvm::Optional<llvm::StringRef> filename);
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SERENE_EXPORT exprs::MaybeAst read(SereneContext &ctx,
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llvm::MemoryBufferRef input,
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llvm::StringRef ns,
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llvm::Optional<llvm::StringRef> filename);
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} // namespace serene::reader
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#endif
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