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// Copyright (C) Filippo Cucchetto <filippocucchetto@gmail.com>
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
#pragma once
#include <cctype>
#include <cstdint>
#include <cstring>
#include <string>
#include <vector>
namespace Nim {
struct SExprLexer {
enum Result {
Finished,
TokenAvailable,
Error
};
enum TokenType : std::size_t {
STRING,
NUMBER,
IDENTIFIER,
OPEN_BRACE,
CLOSE_BRACE,
};
struct Token {
TokenType type;
std::size_t start;
std::size_t end;
};
SExprLexer(const char *data, std::size_t length)
: m_data(data)
, m_dataLength(length)
, m_pos(0)
{}
SExprLexer(const char *data)
: SExprLexer(data, ::strlen(data))
{}
SExprLexer(const std::string &data)
: SExprLexer(data.c_str(), data.length())
{}
const char *data() const
{
return m_data;
}
std::size_t dataLength() const
{
return m_dataLength;
}
static size_t tokenLength(Token &token)
{
return token.end - token.start + 1;
}
std::string tokenValue(Token &token) const
{
return std::string(m_data + token.start, tokenLength(token));
}
Result next(Token &token)
{
while (m_pos < m_dataLength) {
if (m_data[m_pos] == '(') {
token = Token{OPEN_BRACE, m_pos, m_pos + 1};
m_pos++;
return TokenAvailable;
} else if (m_data[m_pos] == ')') {
token = Token{CLOSE_BRACE, m_pos, m_pos + 1};
m_pos++;
return TokenAvailable;
} else if (m_data[m_pos] == '"') {
Token token_tmp {STRING, m_pos, m_pos};
char previous = '"';
m_pos++;
while (true) {
if (m_pos >= m_dataLength)
return Error;
if (m_data[m_pos] == '"' && previous != '\\')
break;
previous = m_data[m_pos];
m_pos++;
}
token_tmp.end = m_pos;
token = std::move(token_tmp);
m_pos++;
return TokenAvailable;
} else if (std::isdigit(m_data[m_pos])) {
bool decimal_separator_found = false;
token = {NUMBER, m_pos, m_pos};
m_pos++;
while (true) {
if (m_pos >= m_dataLength)
break;
if (m_data[m_pos] == ',' || m_data[m_pos] == '.') {
if (decimal_separator_found)
return Error;
decimal_separator_found = true;
} else if (!std::isdigit(m_data[m_pos]))
break;
m_pos++;
}
token.end = m_pos - 1;
return TokenAvailable;
} else if (!std::isspace(m_data[m_pos])) {
token = {IDENTIFIER, m_pos, m_pos};
m_pos++;
while (true) {
if (m_pos >= m_dataLength)
break;
if (std::isspace(m_data[m_pos]) || m_data[m_pos] == '(' || m_data[m_pos] == ')')
break;
m_pos++;
}
token.end = m_pos - 1;
return TokenAvailable;
} else {
m_pos++;
}
}
return Finished;
}
static std::vector<Token> parse(const std::string &data)
{
return parse(data.data(), data.size());
}
static std::vector<Token> parse(const char *data)
{
return parse(data, ::strlen(data));
}
static std::vector<Token> parse(const char *data, std::size_t data_size)
{
std::vector<Token> result;
SExprLexer lexer(data, data_size);
Token token {};
while (lexer.next(token)) {
result.push_back(token);
token = {};
}
return result;
}
private:
const char *m_data = nullptr;
std::size_t m_dataLength = 0;
std::size_t m_pos = 0;
};
} // namespace Nim
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