From: Ben Pfaff Date: Tue, 20 Jul 2010 05:52:18 +0000 (-0700) Subject: lexer: Get rid of lex_negative_to_dash(). X-Git-Tag: v0.7.7~124 X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=740218f508466f16a79939cd97027b99f589d682;p=pspp-builds.git lexer: Get rid of lex_negative_to_dash(). This function stands in the way of replacing the lexer in a straightforward way, because it disrupts the stream of tokens: the lexer can't tell in advance whether, e.g., "-4" is one token or two. Fortunately, it is not used in very many places and is relatively easy to remove. --- diff --git a/src/language/data-io/placement-parser.c b/src/language/data-io/placement-parser.c index e9fe3372..820560df 100644 --- a/src/language/data-io/placement-parser.c +++ b/src/language/data-io/placement-parser.c @@ -293,12 +293,10 @@ execute_placement_format (const struct fmt_spec *format, stores a 1-based column number into *COLUMN if successful, otherwise emits an error message and returns false. */ static bool -parse_column (struct lexer *lexer, int base, int *column) +parse_column (int value, int base, int *column) { assert (base == 0 || base == 1); - if (!lex_force_int (lexer)) - return false; - *column = lex_integer (lexer) - base + 1; + *column = value - base + 1; if (*column < 1) { if (base == 1) @@ -307,7 +305,6 @@ parse_column (struct lexer *lexer, int base, int *column) msg (SE, _("Column positions for fields must not be negative.")); return false; } - lex_get (lexer); return true; } @@ -330,15 +327,18 @@ parse_column_range (struct lexer *lexer, int base, bool *range_specified) { /* First column. */ - if (!parse_column (lexer, base, first_column)) + if (!lex_force_int (lexer) + || !parse_column (lex_integer (lexer), base, first_column)) return false; + lex_get (lexer); /* Last column. */ - lex_negative_to_dash (lexer); - if (lex_match (lexer, T_DASH)) + if (lex_is_integer (lexer) && lex_integer (lexer) < 0) { - if (!parse_column (lexer, base, last_column)) + if (!parse_column (-lex_integer (lexer), base, last_column)) return false; + lex_get (lexer); + if (*last_column < *first_column) { msg (SE, _("The ending column for a field must be " diff --git a/src/language/expressions/parse.c b/src/language/expressions/parse.c index c1035611..79576b44 100644 --- a/src/language/expressions/parse.c +++ b/src/language/expressions/parse.c @@ -499,16 +499,14 @@ match_operator (struct lexer *lexer, const struct operator ops[], size_t op_cnt, const struct operator *op; for (op = ops; op < ops + op_cnt; op++) - { - if (op->token == T_DASH) - lex_negative_to_dash (lexer); - if (lex_match (lexer, op->token)) - { - if (operator != NULL) - *operator = op; - return true; - } - } + if (lex_token (lexer) == op->token) + { + if (op->token != T_NEG_NUM) + lex_get (lexer); + if (operator != NULL) + *operator = op; + return true; + } if (operator != NULL) *operator = NULL; return false; @@ -710,6 +708,7 @@ parse_add (struct lexer *lexer, struct expression *e) { { T_PLUS, OP_ADD, "addition (`+')" }, { T_DASH, OP_SUB, "subtraction (`-')" }, + { T_NEG_NUM, OP_ADD, "subtraction (`-')" }, }; return parse_binary_operators (lexer, e, parse_mul (lexer, e), @@ -752,8 +751,21 @@ parse_exp (struct lexer *lexer, struct expression *e) "That is, `a**b**c' equals `(a**b)**c', not as `a**(b**c)'. " "To disable this warning, insert parentheses."); - return parse_binary_operators (lexer, e, parse_primary (lexer, e), &op, 1, - parse_primary, chain_warning); + union any_node *lhs, *node; + bool negative = false; + + if (lex_token (lexer) == T_NEG_NUM) + { + lhs = expr_allocate_number (e, -lex_tokval (lexer)); + negative = true; + lex_get (lexer); + } + else + lhs = parse_primary (lexer, e); + + node = parse_binary_operators (lexer, e, lhs, &op, 1, + parse_primary, chain_warning); + return negative ? expr_allocate_unary (e, OP_NEG, node) : node; } /* Parses system variables. */ diff --git a/src/language/lexer/lexer.c b/src/language/lexer/lexer.c index b0b530bf..c08c428c 100644 --- a/src/language/lexer/lexer.c +++ b/src/language/lexer/lexer.c @@ -215,13 +215,8 @@ lex_get (struct lexer *lexer) { char *tail; - /* `-' can introduce a negative number, or it can be a - token by itself. If it is not followed by a digit or a - decimal point, it is definitely not a number. - Otherwise, it might be either, but most of the time we - want it as a number. When the syntax calls for a `-' - token, lex_negative_to_dash() must be used to break - negative numbers into two tokens. */ + /* `-' can introduce a negative number, or it can be a token by + itself. */ if (*lexer->prog == '-') { ds_put_byte (&lexer->tokstr, *lexer->prog++); @@ -1134,23 +1129,6 @@ lex_token_representation (struct lexer *lexer) /* Really weird functions. */ -/* Most of the time, a `-' is a lead-in to a negative number. But - sometimes it's actually part of the syntax. If a dash can be part - of syntax then this function is called to rip it off of a - number. */ -void -lex_negative_to_dash (struct lexer *lexer) -{ - if (lexer->token == T_NEG_NUM) - { - lexer->token = T_POS_NUM; - lexer->tokval = -lexer->tokval; - ds_assign_substring (&lexer->tokstr, ds_substr (&lexer->tokstr, 1, SIZE_MAX)); - save_token (lexer); - lexer->token = T_DASH; - } -} - /* Skip a COMMENT command. */ void lex_skip_comment (struct lexer *lexer) diff --git a/src/language/lexer/lexer.h b/src/language/lexer/lexer.h index efdef8a4..82f3fe23 100644 --- a/src/language/lexer/lexer.h +++ b/src/language/lexer/lexer.h @@ -97,7 +97,6 @@ const char *lex_tokid (const struct lexer *); const struct string *lex_tokstr (const struct lexer *); /* Really weird functions. */ -void lex_negative_to_dash (struct lexer *); void lex_skip_comment (struct lexer *); #endif /* !lexer_h */