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Simplify and optimize how keywords are lexed.

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This commit is contained in:
Bob Nystrom
2015-09-17 20:51:24 -07:00
parent dc527c8d86
commit 19f70b4035
1 changed files with 44 additions and 29 deletions
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73
src/vm/wren_compiler.c
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@ -441,6 +441,38 @@ static void initCompiler(Compiler* compiler, Parser* parser, Compiler* parent,
// Lexing ----------------------------------------------------------------------
typedef struct
{
const char* identifier;
size_t length;
TokenType tokenType;
} Keyword;
// The table of reserved words and their associated token types.
static Keyword keywords[] =
{
{"break", 5, TOKEN_BREAK},
{"class", 5, TOKEN_CLASS},
{"construct", 9, TOKEN_CONSTRUCT},
{"else", 4, TOKEN_ELSE},
{"false", 5, TOKEN_FALSE},
{"for", 3, TOKEN_FOR},
{"foreign", 7, TOKEN_FOREIGN},
{"if", 2, TOKEN_IF},
{"import", 6, TOKEN_IMPORT},
{"in", 2, TOKEN_IN},
{"is", 2, TOKEN_IS},
{"null", 4, TOKEN_NULL},
{"return", 6, TOKEN_RETURN},
{"static", 6, TOKEN_STATIC},
{"super", 5, TOKEN_SUPER},
{"this", 4, TOKEN_THIS},
{"true", 4, TOKEN_TRUE},
{"var", 3, TOKEN_VAR},
{"while", 5, TOKEN_WHILE},
{NULL, 0, TOKEN_EOF} // Sentinel to mark the end of the array.
};
// Returns true if [c] is a valid (non-initial) identifier character.
static bool isName(char c)
{
@ -546,15 +578,6 @@ static void skipBlockComment(Parser* parser)
}
}
// Returns true if the current token's text matches [keyword].
static bool isKeyword(Parser* parser, const char* keyword)
{
size_t length = parser->currentChar - parser->tokenStart;
size_t keywordLength = strlen(keyword);
return length == keywordLength &&
strncmp(parser->tokenStart, keyword, length) == 0;
}
// Reads the next character, which should be a hex digit (0-9, a-f, or A-F) and
// returns its numeric value. If the character isn't a hex digit, returns -1.
static int readHexDigit(Parser* parser)
@ -639,26 +662,18 @@ static void readName(Parser* parser, TokenType type)
nextChar(parser);
}
if (isKeyword(parser, "break")) type = TOKEN_BREAK;
else if (isKeyword(parser, "class")) type = TOKEN_CLASS;
else if (isKeyword(parser, "construct")) type = TOKEN_CONSTRUCT;
else if (isKeyword(parser, "else")) type = TOKEN_ELSE;
else if (isKeyword(parser, "false")) type = TOKEN_FALSE;
else if (isKeyword(parser, "for")) type = TOKEN_FOR;
else if (isKeyword(parser, "foreign")) type = TOKEN_FOREIGN;
else if (isKeyword(parser, "if")) type = TOKEN_IF;
else if (isKeyword(parser, "import")) type = TOKEN_IMPORT;
else if (isKeyword(parser, "in")) type = TOKEN_IN;
else if (isKeyword(parser, "is")) type = TOKEN_IS;
else if (isKeyword(parser, "null")) type = TOKEN_NULL;
else if (isKeyword(parser, "return")) type = TOKEN_RETURN;
else if (isKeyword(parser, "static")) type = TOKEN_STATIC;
else if (isKeyword(parser, "super")) type = TOKEN_SUPER;
else if (isKeyword(parser, "this")) type = TOKEN_THIS;
else if (isKeyword(parser, "true")) type = TOKEN_TRUE;
else if (isKeyword(parser, "var")) type = TOKEN_VAR;
else if (isKeyword(parser, "while")) type = TOKEN_WHILE;
// Update the type if it's a keyword.
size_t length = parser->currentChar - parser->tokenStart;
for (int i = 0; keywords[i].identifier != NULL; i++)
{
if (length == keywords[i].length &&
memcmp(parser->tokenStart, keywords[i].identifier, length) == 0)
{
type = keywords[i].tokenType;
break;
}
}
makeToken(parser, type);
}