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Parser: Allow specifying custom depth for optimization #1

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13 changes: 8 additions & 5 deletions include/sexp/parser.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -33,14 +33,14 @@ class Parser
public:
enum { USE_ARRAYS = true };

static Value from_string(std::string const& str, bool use_arrays = false);
static Value from_stream(std::istream& stream, bool use_arrays = false);
static Value from_string(std::string const& str, bool use_arrays = false, int depth = -1);
static Value from_stream(std::istream& stream, bool use_arrays = false, int depth = -1);

static std::vector<Value> from_string_many(std::string const& str, bool use_arrays = false);
static std::vector<Value> from_stream_many(std::istream& stream, bool use_arrays = false);
static std::vector<Value> from_string_many(std::string const& str, bool use_arrays = false, int depth = -1);
static std::vector<Value> from_stream_many(std::istream& stream, bool use_arrays = false, int depth = -1);

public:
Parser(Lexer& lexer);
Parser(Lexer& lexer, int depth = -1);
~Parser();

private:
Expand All @@ -51,7 +51,10 @@ class Parser

private:
Lexer& m_lexer;
const int m_depth;

Lexer::TokenType m_token;
int m_current_depth;

private:
Parser(const Parser&);
Expand Down
14 changes: 14 additions & 0 deletions include/sexp/value.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -204,6 +204,7 @@ class Value
inline bool is_integer() const { return m_type == Type::INTEGER; }
inline bool is_real() const { return (m_type == Type::REAL || m_type == Type::INTEGER); }
inline bool is_string() const { return m_type == Type::STRING; }
inline bool is_translatable_string() const;
inline bool is_symbol() const { return m_type == Type::SYMBOL; }
inline bool is_cons() const { return m_type == Type::CONS; }
inline bool is_array() const { return m_type == Type::ARRAY; }
Expand Down Expand Up @@ -343,6 +344,19 @@ Value::operator==(Value const& rhs) const
}
}

inline bool
Value::is_translatable_string() const
{
if (m_type != Type::ARRAY)
return false;

const std::vector<Value>& array = *m_data.m_array;
return array.size() == 2 &&
array[0].is_symbol() &&
array[0].as_string() == "_" &&
array[1].is_string();
}

inline Value const&
Value::get_car() const
{
Expand Down
105 changes: 86 additions & 19 deletions src/parser.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -27,17 +27,17 @@
namespace sexp {

Value
Parser::from_string(std::string const& str, bool use_arrays)
Parser::from_string(std::string const& str, bool use_arrays, int depth)
{
std::istringstream is(str);
return from_stream(is);
return from_stream(is, use_arrays, depth);
}

Value
Parser::from_stream(std::istream& stream, bool use_arrays)
Parser::from_stream(std::istream& stream, bool use_arrays, int depth)
{
Lexer lexer(stream, use_arrays);
Parser parser(lexer);
Parser parser(lexer, depth);
Value result = parser.read();
if (parser.m_token != Lexer::TOKEN_EOF)
{
Expand All @@ -47,23 +47,25 @@ Parser::from_stream(std::istream& stream, bool use_arrays)
}

std::vector<Value>
Parser::from_string_many(std::string const& str, bool use_arrays)
Parser::from_string_many(std::string const& str, bool use_arrays, int depth)
{
std::istringstream is(str);
return from_stream_many(is);
return from_stream_many(is, use_arrays, depth);
}

std::vector<Value>
Parser::from_stream_many(std::istream& stream, bool use_arrays)
Parser::from_stream_many(std::istream& stream, bool use_arrays, int depth)
{
Lexer lexer(stream, use_arrays);
Parser parser(lexer);
Parser parser(lexer, depth);
return parser.read_many();
}

Parser::Parser(Lexer& lexer) :
Parser::Parser(Lexer& lexer, int depth) :
m_lexer(lexer),
m_token(m_lexer.get_next_token())
m_depth(depth),
m_token(m_lexer.get_next_token()),
m_current_depth(-1)
{
}

Expand Down Expand Up @@ -101,20 +103,36 @@ Parser::read()
{
case Lexer::TOKEN_OPEN_PAREN:
m_token = m_lexer.get_next_token();
if(m_token == Lexer::TOKEN_CLOSE_PAREN)
if (m_token == Lexer::TOKEN_CLOSE_PAREN)
break;

++m_current_depth;
// If a depth is specified, do not parse objects below it.
if (m_depth >= 0 && m_current_depth > m_depth)
{
result = Value::nil();
while (m_token != Lexer::TOKEN_CLOSE_PAREN)
{
if (m_token == Lexer::TOKEN_OPEN_PAREN)
read(); // Recursively go through the tokens of child objects.
else
m_token = m_lexer.get_next_token();
}
}
else
{
result = Value::cons(read(), Value::nil());
Value* cur = &result;
while(m_token != Lexer::TOKEN_CLOSE_PAREN)
while (m_token != Lexer::TOKEN_CLOSE_PAREN)
{
if (m_token == Lexer::TOKEN_DOT)
{
m_token = m_lexer.get_next_token();
cur->set_cdr(read());

Value val = read();
// Do not include values that would be nil for being below the specified depth.
if (m_depth < 0 || m_current_depth != m_depth || !val.is_nil())
cur->set_cdr(std::move(val));

if (m_token != Lexer::TOKEN_CLOSE_PAREN)
{
parse_error("Expected ')'");
Expand All @@ -123,11 +141,17 @@ Parser::read()
}
else
{
cur->set_cdr(Value::cons(read(), Value::nil()));
cur = &cur->get_cdr();
Value val = read();
// Do not include values that would be nil for being below the specified depth.
if (m_depth < 0 || m_current_depth != m_depth || !val.is_nil())
{
cur->set_cdr(Value::cons(std::move(val), Value::nil()));
cur = &cur->get_cdr();
}
}
}
}
--m_current_depth;
break;

case Lexer::TOKEN_SYMBOL:
Expand Down Expand Up @@ -155,16 +179,59 @@ Parser::read()
break;

case Lexer::TOKEN_ARRAY_START:
m_token = m_lexer.get_next_token();
if (m_token == Lexer::TOKEN_CLOSE_PAREN)
break;

++m_current_depth;
// If a depth is specified, do not parse arrays below it.
if (m_depth >= 0 && m_current_depth > m_depth)
{
while (m_token != Lexer::TOKEN_CLOSE_PAREN)
{
if (m_token == Lexer::TOKEN_ARRAY_START)
{
read(); // Recursively go through the tokens of child arrays.
}
else
{
// If the array is just below the specified depth, but contains a translatable string, parse it.
if (m_current_depth - 1 == m_depth &&
m_token == Lexer::TOKEN_SYMBOL && m_lexer.get_string() == "_")
{
m_token = m_lexer.get_next_token();
if (m_token == Lexer::TOKEN_STRING)
{
const std::string str = m_lexer.get_string();
m_token = m_lexer.get_next_token();
if (m_token == Lexer::TOKEN_CLOSE_PAREN)
{
result = Value::array({ Value::symbol("_"), Value::string(str) });
break;
}
}
}
else
{
m_token = m_lexer.get_next_token();
}
}
}
}
else
{
m_token = m_lexer.get_next_token();
std::vector<Value> arr;
do
{
arr.emplace_back(read());
Value val = read();
// Do not include values that would be nil for being below the specified depth.
if (m_depth < 0 || m_current_depth != m_depth || !val.is_nil())
arr.push_back(std::move(val));
}
while(m_token != Lexer::TOKEN_CLOSE_PAREN);
while (m_token != Lexer::TOKEN_CLOSE_PAREN);
result = Value::array(std::move(arr));
}
--m_current_depth;
break;

case Lexer::TOKEN_EOF:
Expand Down
25 changes: 25 additions & 0 deletions tests/parser_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -150,6 +150,23 @@ TEST(ParserTest, parse_symbol)
}
}

TEST(ParserTest, parse_cons)
{
char const* sx_str = "(1 \"foo\" (bar))";
auto sx = sexp::Parser::from_string(sx_str, false);
ASSERT_TRUE(sx.is_cons());
ASSERT_EQ(sexp::Value::Type::CONS, sx.get_type());
ASSERT_EQ(sx_str, sx.str());
}

TEST(ParserTest, parse_cons_depth_limit)
{
auto sx = sexp::Parser::from_string("(1 \"foo\" (bar foo (foo 1) 2 (\"bar\" . 4)))", false, 1);
ASSERT_TRUE(sx.is_cons());
ASSERT_EQ(sexp::Value::Type::CONS, sx.get_type());
ASSERT_EQ("(1 \"foo\" (bar foo 2))", sx.str());
}

TEST(ParserTest, parse_array)
{
char const* sx_str = "#(1 \"foo\" #(bar))";
Expand All @@ -159,6 +176,14 @@ TEST(ParserTest, parse_array)
ASSERT_EQ(sx_str, sx.str());
}

TEST(ParserTest, parse_array_depth_limit)
{
auto sx = sexp::Parser::from_string("#(1 \"foo\" #(bar foo #(foo 1) 2 #(\"bar\" 4)))", false, 1);
ASSERT_TRUE(sx.is_array());
ASSERT_EQ(sexp::Value::Type::ARRAY, sx.get_type());
ASSERT_EQ("#(1 \"foo\" #(bar foo 2))", sx.str());
}

// FIXME: Compare data structure or use simple strings?!
// "(foo . bar)" as string is ambigous in the current parser as . can be handled as symbol, not pair
TEST(ParserTest, simple_pair)
Expand Down