Lexer: Added string support

This commit is contained in:
Paul Beckingham 2015-12-20 15:02:53 -05:00
parent d236315450
commit 31c145ef9e
3 changed files with 300 additions and 3 deletions

View file

@ -51,7 +51,8 @@ bool Lexer::token (std::string& token, Lexer::Type& type)
if (isEOS ())
return false;
if (isWord (token, type))
if (isString (token, type, "'\"") ||
isWord (token, type))
return true;
return false;
@ -99,6 +100,15 @@ bool Lexer::isWhitespace (int c)
c == 0x3000); // ideographic space Common Separator, space
}
////////////////////////////////////////////////////////////////////////////////
// Digits 0-9 a-f A-F.
bool Lexer::isHexDigit (int c)
{
return (c >= '0' && c <= '9') ||
(c >= 'a' && c <= 'f') ||
(c >= 'A' && c <= 'F');
}
////////////////////////////////////////////////////////////////////////////////
bool Lexer::isSingleCharOperator (int c)
{
@ -117,12 +127,56 @@ bool Lexer::isSingleCharOperator (int c)
c == '~'; // Pattern match
}
////////////////////////////////////////////////////////////////////////////////
bool Lexer::isHardBoundary (int left, int right)
{
// EOS
if (right == '\0')
return true;
// FILTER operators that don't need to be surrounded by whitespace.
if (left == '(' ||
left == ')' ||
right == '(' ||
right == ')')
return true;
return false;
}
////////////////////////////////////////////////////////////////////////////////
bool Lexer::isEOS () const
{
return _cursor >= _eos;
}
////////////////////////////////////////////////////////////////////////////////
// Converts '0' -> 0
// '9' -> 9
// 'a'/'A' -> 10
// 'f'/'F' -> 15
int Lexer::hexToInt (int c)
{
if (c >= '0' && c <= '9') return (c - '0');
else if (c >= 'a' && c <= 'f') return (c - 'a' + 10);
else return (c - 'A' + 10);
}
////////////////////////////////////////////////////////////////////////////////
int Lexer::hexToInt (int c0, int c1)
{
return (hexToInt (c0) << 4) + hexToInt (c1);
}
////////////////////////////////////////////////////////////////////////////////
int Lexer::hexToInt (int c0, int c1, int c2, int c3)
{
return (hexToInt (c0) << 12) +
(hexToInt (c1) << 8) +
(hexToInt (c2) << 4) +
hexToInt (c3);
}
////////////////////////////////////////////////////////////////////////////////
std::string Lexer::trimLeft (const std::string& in, const std::string& t /*= " "*/)
{
@ -149,6 +203,24 @@ std::string Lexer::trim (const std::string& in, const std::string& t /*= " "*/)
return trimLeft (trimRight (in, t), t);
}
////////////////////////////////////////////////////////////////////////////////
// Lexer::Type::string
// '|"
// [ U+XXXX | \uXXXX | \" | \' | \\ | \/ | \b | \f | \n | \r | \t | . ]
// '|"
bool Lexer::isString (std::string& token, Lexer::Type& type, const std::string& quotes)
{
std::size_t marker = _cursor;
if (readWord (_text, quotes, marker, token))
{
type = Lexer::Type::string;
_cursor = marker;
return true;
}
return false;
}
////////////////////////////////////////////////////////////////////////////////
// Lexer::Type::word
// [^\s]+
@ -173,3 +245,170 @@ bool Lexer::isWord (std::string& token, Lexer::Type& type)
}
////////////////////////////////////////////////////////////////////////////////
// Full implementation of a quoted word. Includes:
// '\''
// '"'
// "'"
// "\""
// 'one two'
// Result includes the quotes.
bool Lexer::readWord (
const std::string& text,
const std::string& quotes,
std::string::size_type& cursor,
std::string& word)
{
if (quotes.find (text[cursor]) == std::string::npos)
return false;
std::string::size_type eos = text.length ();
int quote = text[cursor++];
word = quote;
int c;
while ((c = text[cursor]))
{
// Quoted word ends on a quote.
if (quote && quote == c)
{
word += utf8_character (utf8_next_char (text, cursor));
break;
}
// Unicode U+XXXX or \uXXXX codepoint.
else if (eos - cursor >= 6 &&
((text[cursor + 0] == 'U' && text[cursor + 1] == '+') ||
(text[cursor + 0] == '\\' && text[cursor + 1] == 'u')) &&
isHexDigit (text[cursor + 2]) &&
isHexDigit (text[cursor + 3]) &&
isHexDigit (text[cursor + 4]) &&
isHexDigit (text[cursor + 5]))
{
word += utf8_character (
hexToInt (
text[cursor + 2],
text[cursor + 3],
text[cursor + 4],
text[cursor + 5]));
cursor += 6;
}
// An escaped thing.
else if (c == '\\')
{
c = text[++cursor];
switch (c)
{
case '"': word += (char) 0x22; ++cursor; break;
case '\'': word += (char) 0x27; ++cursor; break;
case '\\': word += (char) 0x5C; ++cursor; break;
case 'b': word += (char) 0x08; ++cursor; break;
case 'f': word += (char) 0x0C; ++cursor; break;
case 'n': word += (char) 0x0A; ++cursor; break;
case 'r': word += (char) 0x0D; ++cursor; break;
case 't': word += (char) 0x09; ++cursor; break;
case 'v': word += (char) 0x0B; ++cursor; break;
// This pass-through default case means that anything can be escaped
// harmlessly. In particular 'quote' is included, if it not one of the
// above characters.
default: word += (char) c; ++cursor; break;
}
}
// Ordinary character.
else
word += utf8_character (utf8_next_char (text, cursor));
}
// Verify termination.
return word[0] == quote &&
word[word.length () - 1] == quote &&
word.length () >= 2;
}
////////////////////////////////////////////////////////////////////////////////
// Full implementation of an unquoted word. Includes:
// one\ two
// abcU+0020def
// abc\u0020def
// a\tb
//
// Ends at:
// Lexer::isEOS
// Lexer::isWhitespace
// Lexer::isHardBoundary
bool Lexer::readWord (
const std::string& text,
std::string::size_type& cursor,
std::string& word)
{
std::string::size_type eos = text.length ();
word = "";
int c;
int prev = 0;
while ((c = text[cursor])) // Handles EOS.
{
// Unquoted word ends on white space.
if (Lexer::isWhitespace (c))
break;
// Parentheses mostly.
if (prev && Lexer::isHardBoundary (prev, c))
break;
// Unicode U+XXXX or \uXXXX codepoint.
else if (eos - cursor >= 6 &&
((text[cursor + 0] == 'U' && text[cursor + 1] == '+') ||
(text[cursor + 0] == '\\' && text[cursor + 1] == 'u')) &&
isHexDigit (text[cursor + 2]) &&
isHexDigit (text[cursor + 3]) &&
isHexDigit (text[cursor + 4]) &&
isHexDigit (text[cursor + 5]))
{
word += utf8_character (
hexToInt (
text[cursor + 2],
text[cursor + 3],
text[cursor + 4],
text[cursor + 5]));
cursor += 6;
}
// An escaped thing.
else if (c == '\\')
{
c = text[++cursor];
switch (c)
{
case '"': word += (char) 0x22; ++cursor; break;
case '\'': word += (char) 0x27; ++cursor; break;
case '\\': word += (char) 0x5C; ++cursor; break;
case 'b': word += (char) 0x08; ++cursor; break;
case 'f': word += (char) 0x0C; ++cursor; break;
case 'n': word += (char) 0x0A; ++cursor; break;
case 'r': word += (char) 0x0D; ++cursor; break;
case 't': word += (char) 0x09; ++cursor; break;
case 'v': word += (char) 0x0B; ++cursor; break;
// This pass-through default case means that anything can be escaped
// harmlessly. In particular 'quote' is included, if it not one of the
// above characters.
default: word += (char) c; ++cursor; break;
}
}
// Ordinary character.
else
word += utf8_character (utf8_next_char (text, cursor));
prev = c;
}
return word.length () > 0 ? true : false;
}
////////////////////////////////////////////////////////////////////////////////

View file

@ -35,20 +35,29 @@
class Lexer
{
public:
enum class Type { word };
enum class Type { string,
word };
Lexer (const std::string&);
bool token (std::string&, Lexer::Type&);
// Static helpers.
static bool isWhitespace (int);
static bool isHexDigit (int);
static bool isSingleCharOperator (int);
static bool isHardBoundary (int, int);
static bool readWord (const std::string&, const std::string&, std::string::size_type&, std::string&);
static bool readWord (const std::string&, std::string::size_type&, std::string&);
static int hexToInt (int);
static int hexToInt (int, int);
static int hexToInt (int, int, int, int);
static std::string trimLeft (const std::string& in, const std::string& t = " ");
static std::string trimRight (const std::string& in, const std::string& t = " ");
static std::string trim (const std::string& in, const std::string& t = " ");
// Stream Classifiers.
bool isEOS () const;
bool isString (std::string&, Lexer::Type&, const std::string&);
bool isWord (std::string&, Lexer::Type&);
private:

View file

@ -34,7 +34,7 @@
////////////////////////////////////////////////////////////////////////////////
int main (int, char**)
{
UnitTest t (50);
UnitTest t (74);
std::vector <std::pair <std::string, Lexer::Type>> tokens;
std::string token;
@ -77,6 +77,55 @@ int main (int, char**)
Lexer l1 (" \t ");
t.notok (l1.token (token, type), "' \\t ' --> no tokens");
// static bool readWord (const std::string&, const std::string&, std::string::size_type&, std::string&);
std::string::size_type cursor = 0;
std::string word;
t.ok (Lexer::readWord ("'one two'", "'\"", cursor, word), "readWord ''one two'' --> true");
t.is (word, "'one two'", " word '" + word + "'");
t.is ((int)cursor, 9, " cursor");
// Unterminated quoted string is invalid.
cursor = 0;
t.notok (Lexer::readWord ("'one", "'\"", cursor, word), "readWord ''one' --> false");
// static bool readWord (const std::string&, std::string::size_type&, std::string&);
cursor = 0;
t.ok (Lexer::readWord ("input", cursor, word), "readWord 'input' --> true");
t.is (word, "input", " word '" + word + "'");
t.is ((int)cursor, 5, " cursor");
cursor = 0;
t.ok (Lexer::readWord ("one\\ two", cursor, word), "readWord 'one\\ two' --> true");
t.is (word, "one two", " word '" + word + "'");
t.is ((int)cursor, 8, " cursor");
cursor = 0;
t.ok (Lexer::readWord ("\\u20A43", cursor, word), "readWord '\\u20A43' --> true");
t.is (word, "₤3", " word '" + word + "'");
t.is ((int)cursor, 7, " cursor");
cursor = 0;
t.ok (Lexer::readWord ("U+20AC4", cursor, word), "readWord '\\u20AC4' --> true");
t.is (word, "€4", " word '" + word + "'");
t.is ((int)cursor, 7, " cursor");
std::string text = "one 'two' three\\ four";
cursor = 0;
t.ok (Lexer::readWord (text, cursor, word), "readWord \"one 'two' three\\ four\" --> true");
t.is (word, "one", " word '" + word + "'");
cursor++;
t.ok (Lexer::readWord (text, cursor, word), "readWord \"one 'two' three\\ four\" --> true");
t.is (word, "'two'", " word '" + word + "'");
cursor++;
t.ok (Lexer::readWord (text, cursor, word), "readWord \"one 'two' three\\ four\" --> true");
t.is (word, "three four", " word '" + word + "'");
text = "one ";
cursor = 0;
t.ok (Lexer::readWord (text, cursor, word), "readWord \"one \" --> true");
t.is (word, "one", " word '" + word + "'");
// std::string Lexer::trimLeft (const std::string& in, const std::string&)
t.is (Lexer::trimLeft (""), "", "Lexer::trimLeft '' -> ''");
t.is (Lexer::trimLeft (" "), "", "Lexer::trimLeft ' ' -> ''");