Lexical Scanner

Lexical Scanner — a general purpose lexical scanner

Types and Values

struct GScanner
struct GScannerConfig
#define G_CSET_a_2_z
#define G_CSET_A_2_Z
#define G_CSET_DIGITS
#define G_CSET_LATINC
#define G_CSET_LATINS
enum GTokenType
union GTokenValue
enum GErrorType

Includes

#include <glib.h>

Description

The GScanner and its associated functions provide a general purpose lexical scanner.

Functions

g_scanner_new ()

GScanner *
g_scanner_new (const GScannerConfig *config_templ);

Creates a new GScanner.

The config_templ structure specifies the initial settings of the scanner, which are copied into the GScanner config field. If you pass NULL then the default settings are used.

Parameters

config_templ

the initial scanner settings

 

Returns

the new GScanner


g_scanner_destroy ()

void
g_scanner_destroy (GScanner *scanner);

Frees all memory used by the GScanner.

Parameters

scanner

a GScanner

 

g_scanner_input_file ()

void
g_scanner_input_file (GScanner *scanner,
                      gint input_fd);

Prepares to scan a file.

Parameters

scanner

a GScanner

 

input_fd

a file descriptor

 

g_scanner_sync_file_offset ()

void
g_scanner_sync_file_offset (GScanner *scanner);

Rewinds the filedescriptor to the current buffer position and blows the file read ahead buffer. This is useful for third party uses of the scanners filedescriptor, which hooks onto the current scanning position.

Parameters

scanner

a GScanner

 

g_scanner_input_text ()

void
g_scanner_input_text (GScanner *scanner,
                      const gchar *text,
                      guint text_len);

Prepares to scan a text buffer.

Parameters

scanner

a GScanner

 

text

the text buffer to scan

 

text_len

the length of the text buffer

 

g_scanner_peek_next_token ()

GTokenType
g_scanner_peek_next_token (GScanner *scanner);

Parses the next token, without removing it from the input stream. The token data is placed in the next_token , next_value , next_line , and next_position fields of the GScanner structure.

Note that, while the token is not removed from the input stream (i.e. the next call to g_scanner_get_next_token() will return the same token), it will not be reevaluated. This can lead to surprising results when changing scope or the scanner configuration after peeking the next token. Getting the next token after switching the scope or configuration will return whatever was peeked before, regardless of any symbols that may have been added or removed in the new scope.

Parameters

scanner

a GScanner

 

Returns

the type of the token


g_scanner_get_next_token ()

GTokenType
g_scanner_get_next_token (GScanner *scanner);

Parses the next token just like g_scanner_peek_next_token() and also removes it from the input stream. The token data is placed in the token , value , line , and position fields of the GScanner structure.

Parameters

scanner

a GScanner

 

Returns

the type of the token


g_scanner_eof ()

gboolean
g_scanner_eof (GScanner *scanner);

Returns TRUE if the scanner has reached the end of the file or text buffer.

Parameters

scanner

a GScanner

 

Returns

TRUE if the scanner has reached the end of the file or text buffer


g_scanner_cur_line ()

guint
g_scanner_cur_line (GScanner *scanner);

Returns the current line in the input stream (counting from 1). This is the line of the last token parsed via g_scanner_get_next_token().

Parameters

scanner

a GScanner

 

Returns

the current line


g_scanner_cur_position ()

guint
g_scanner_cur_position (GScanner *scanner);

Returns the current position in the current line (counting from 0). This is the position of the last token parsed via g_scanner_get_next_token().

Parameters

scanner

a GScanner

 

Returns

the current position on the line


g_scanner_cur_token ()

GTokenType
g_scanner_cur_token (GScanner *scanner);

Gets the current token type. This is simply the token field in the GScanner structure.

Parameters

scanner

a GScanner

 

Returns

the current token type


g_scanner_cur_value ()

GTokenValue
g_scanner_cur_value (GScanner *scanner);

Gets the current token value. This is simply the value field in the GScanner structure.

Parameters

scanner

a GScanner

 

Returns

the current token value


g_scanner_set_scope ()

guint
g_scanner_set_scope (GScanner *scanner,
                     guint scope_id);

Sets the current scope.

Parameters

scanner

a GScanner

 

scope_id

the new scope id

 

Returns

the old scope id


g_scanner_scope_add_symbol ()

void
g_scanner_scope_add_symbol (GScanner *scanner,
                            guint scope_id,
                            const gchar *symbol,
                            gpointer value);

Adds a symbol to the given scope.

Parameters

scanner

a GScanner

 

scope_id

the scope id

 

symbol

the symbol to add

 

value

the value of the symbol

 

g_scanner_scope_foreach_symbol ()

void
g_scanner_scope_foreach_symbol (GScanner *scanner,
                                guint scope_id,
                                GHFunc func,
                                gpointer user_data);

Calls the given function for each of the symbol/value pairs in the given scope of the GScanner. The function is passed the symbol and value of each pair, and the given user_data parameter.

Parameters

scanner

a GScanner

 

scope_id

the scope id

 

func

the function to call for each symbol/value pair

 

user_data

user data to pass to the function

 

g_scanner_scope_lookup_symbol ()

gpointer
g_scanner_scope_lookup_symbol (GScanner *scanner,
                               guint scope_id,
                               const gchar *symbol);

Looks up a symbol in a scope and return its value. If the symbol is not bound in the scope, NULL is returned.

Parameters

scanner

a GScanner

 

scope_id

the scope id

 

symbol

the symbol to look up

 

Returns

the value of symbol in the given scope, or NULL if symbol is not bound in the given scope.


g_scanner_scope_remove_symbol ()

void
g_scanner_scope_remove_symbol (GScanner *scanner,
                               guint scope_id,
                               const gchar *symbol);

Removes a symbol from a scope.

Parameters

scanner

a GScanner

 

scope_id

the scope id

 

symbol

the symbol to remove

 

g_scanner_add_symbol()

#define             g_scanner_add_symbol( scanner, symbol, value )

g_scanner_add_symbol has been deprecated since version 2.2 and should not be used in newly-written code.

Use g_scanner_scope_add_symbol() instead.

Adds a symbol to the default scope.

Parameters

scanner

a GScanner

 

symbol

the symbol to add

 

value

the value of the symbol

 

g_scanner_remove_symbol()

#define             g_scanner_remove_symbol( scanner, symbol )

g_scanner_remove_symbol has been deprecated since version 2.2 and should not be used in newly-written code.

Use g_scanner_scope_remove_symbol() instead.

Removes a symbol from the default scope.

Parameters

scanner

a GScanner

 

symbol

the symbol to remove

 

g_scanner_foreach_symbol()

#define             g_scanner_foreach_symbol( scanner, func, data )

g_scanner_foreach_symbol has been deprecated since version 2.2 and should not be used in newly-written code.

Use g_scanner_scope_foreach_symbol() instead.

Calls a function for each symbol in the default scope.

Parameters

scanner

a GScanner

 

func

the function to call with each symbol

 

data

data to pass to the function

 

g_scanner_freeze_symbol_table()

#define             g_scanner_freeze_symbol_table(scanner)

g_scanner_freeze_symbol_table has been deprecated since version 2.2 and should not be used in newly-written code.

This macro does nothing.

There is no reason to use this macro, since it does nothing.

Parameters

scanner

a GScanner

 

g_scanner_thaw_symbol_table()

#define             g_scanner_thaw_symbol_table(scanner)

g_scanner_thaw_symbol_table has been deprecated since version 2.2 and should not be used in newly-written code.

This macro does nothing.

There is no reason to use this macro, since it does nothing.

Parameters

scanner

a GScanner

 

g_scanner_lookup_symbol ()

gpointer
g_scanner_lookup_symbol (GScanner *scanner,
                         const gchar *symbol);

Looks up a symbol in the current scope and return its value. If the symbol is not bound in the current scope, NULL is returned.

Parameters

scanner

a GScanner

 

symbol

the symbol to look up

 

Returns

the value of symbol in the current scope, or NULL if symbol is not bound in the current scope


g_scanner_warn ()

void
g_scanner_warn (GScanner *scanner,
                const gchar *format,
                ...);

Outputs a warning message, via the GScanner message handler.

Parameters

scanner

a GScanner

 

format

the message format. See the printf() documentation

 

...

the parameters to insert into the format string

 

g_scanner_error ()

void
g_scanner_error (GScanner *scanner,
                 const gchar *format,
                 ...);

Outputs an error message, via the GScanner message handler.

Parameters

scanner

a GScanner

 

format

the message format. See the printf() documentation

 

...

the parameters to insert into the format string

 

g_scanner_unexp_token ()

void
g_scanner_unexp_token (GScanner *scanner,
                       GTokenType expected_token,
                       const gchar *identifier_spec,
                       const gchar *symbol_spec,
                       const gchar *symbol_name,
                       const gchar *message,
                       gint is_error);

Outputs a message through the scanner's msg_handler, resulting from an unexpected token in the input stream. Note that you should not call g_scanner_peek_next_token() followed by g_scanner_unexp_token() without an intermediate call to g_scanner_get_next_token(), as g_scanner_unexp_token() evaluates the scanner's current token (not the peeked token) to construct part of the message.

Parameters

scanner

a GScanner

 

expected_token

the expected token

 

identifier_spec

a string describing how the scanner's user refers to identifiers (NULL defaults to "identifier"). This is used if expected_token is G_TOKEN_IDENTIFIER or G_TOKEN_IDENTIFIER_NULL.

 

symbol_spec

a string describing how the scanner's user refers to symbols (NULL defaults to "symbol"). This is used if expected_token is G_TOKEN_SYMBOL or any token value greater than G_TOKEN_LAST.

 

symbol_name

the name of the symbol, if the scanner's current token is a symbol.

 

message

a message string to output at the end of the warning/error, or NULL.

 

is_error

if TRUE it is output as an error. If FALSE it is output as a warning.

 

GScannerMsgFunc ()

void
(*GScannerMsgFunc) (GScanner *scanner,
                    gchar *message,
                    gboolean error);

Specifies the type of the message handler function.

Parameters

scanner

a GScanner

 

message

the message

 

error

TRUE if the message signals an error, FALSE if it signals a warning.

 

Types and Values

struct GScanner

struct GScanner {
  /* unused fields */
  gpointer		user_data;
  guint			max_parse_errors;
  
  /* g_scanner_error() increments this field */
  guint			parse_errors;
  
  /* name of input stream, featured by the default message handler */
  const gchar		*input_name;
  
  /* quarked data */
  GData			*qdata;
  
  /* link into the scanner configuration */
  GScannerConfig *config;
  
  /* fields filled in after g_scanner_get_next_token() */
  GTokenType		token;
  GTokenValue		value;
  guint			line;
  guint			position;
  
  /* fields filled in after g_scanner_peek_next_token() */
  GTokenType		next_token;
  GTokenValue		next_value;
  guint			next_line;
  guint			next_position;

  /* handler function for _warn and _error */
  GScannerMsgFunc msg_handler;
};

The data structure representing a lexical scanner.

You should set input_name after creating the scanner, since it is used by the default message handler when displaying warnings and errors. If you are scanning a file, the filename would be a good choice.

The user_data and max_parse_errors fields are not used. If you need to associate extra data with the scanner you can place them here.

If you want to use your own message handler you can set the msg_handler field. The type of the message handler function is declared by GScannerMsgFunc.

Members

gpointer user_data;

unused

 

guint max_parse_errors;

unused

 

guint parse_errors;

g_scanner_error() increments this field

 

const gchar *input_name;

name of input stream, featured by the default message handler

 

GData *qdata;

quarked data

 

GScannerConfig *config;

link into the scanner configuration

 

GTokenType token;

token parsed by the last g_scanner_get_next_token()

 

GTokenValue value;

value of the last token from g_scanner_get_next_token()

 

guint line;

line number of the last token from g_scanner_get_next_token()

 

guint position;

char number of the last token from g_scanner_get_next_token()

 

GTokenType next_token;

token parsed by the last g_scanner_peek_next_token()

 

GTokenValue next_value;

value of the last token from g_scanner_peek_next_token()

 

guint next_line;

line number of the last token from g_scanner_peek_next_token()

 

guint next_position;

char number of the last token from g_scanner_peek_next_token()

 

GScannerMsgFunc msg_handler;

handler function for _warn and _error

 

struct GScannerConfig

struct GScannerConfig {
  /* Character sets
   */
  gchar		*cset_skip_characters;		/* default: " \t\n" */
  gchar		*cset_identifier_first;
  gchar		*cset_identifier_nth;
  gchar		*cpair_comment_single;		/* default: "#\n" */
  
  /* Should symbol lookup work case sensitive?
   */
  guint		case_sensitive : 1;
  
  /* Boolean values to be adjusted "on the fly"
   * to configure scanning behaviour.
   */
  guint		skip_comment_multi : 1;		/* C like comment */
  guint		skip_comment_single : 1; /* single line comment */
  guint		scan_comment_multi : 1;		/* scan multi line comments? */
  guint		scan_identifier : 1;
  guint		scan_identifier_1char : 1;
  guint		scan_identifier_NULL : 1;
  guint		scan_symbols : 1;
  guint		scan_binary : 1;
  guint		scan_octal : 1;
  guint		scan_float : 1;
  guint		scan_hex : 1;			/* '0x0ff0' */
  guint		scan_hex_dollar : 1;		/* '$0ff0' */
  guint		scan_string_sq : 1;		/* string: 'anything' */
  guint		scan_string_dq : 1;		/* string: "\\-escapes!\n" */
  guint		numbers_2_int : 1;		/* bin, octal, hex => int */
  guint		int_2_float : 1;		/* int => G_TOKEN_FLOAT? */
  guint		identifier_2_string : 1;
  guint		char_2_token : 1;		/* return G_TOKEN_CHAR? */
  guint		symbol_2_token : 1;
  guint		scope_0_fallback : 1;		/* try scope 0 on lookups? */
  guint		store_int64 : 1; 		/* use value.v_int64 rather than v_int */
};

Specifies the GScanner parser configuration. Most settings can be changed during the parsing phase and will affect the lexical parsing of the next unpeeked token.

Members

gchar *cset_skip_characters;

specifies which characters should be skipped by the scanner (the default is the whitespace characters: space, tab, carriage-return and line-feed).

 

gchar *cset_identifier_first;

specifies the characters which can start identifiers (the default is G_CSET_a_2_z, "_", and G_CSET_A_2_Z).

 

gchar *cset_identifier_nth;

specifies the characters which can be used in identifiers, after the first character (the default is G_CSET_a_2_z, "_0123456789", G_CSET_A_2_Z, G_CSET_LATINS, G_CSET_LATINC).

 

gchar *cpair_comment_single;

specifies the characters at the start and end of single-line comments. The default is "#\n" which means that single-line comments start with a '#' and continue until a '\n' (end of line).

 

guint case_sensitive : 1;

specifies if symbols are case sensitive (the default is FALSE).

 

guint skip_comment_multi : 1;

specifies if multi-line comments are skipped and not returned as tokens (the default is TRUE).

 

guint skip_comment_single : 1;

specifies if single-line comments are skipped and not returned as tokens (the default is TRUE).

 

guint scan_comment_multi : 1;

specifies if multi-line comments are recognized (the default is TRUE).

 

guint scan_identifier : 1;

specifies if identifiers are recognized (the default is TRUE).

 

guint scan_identifier_1char : 1;

specifies if single-character identifiers are recognized (the default is FALSE).

 

guint scan_identifier_NULL : 1;

specifies if NULL is reported as G_TOKEN_IDENTIFIER_NULL (the default is FALSE).

 

guint scan_symbols : 1;

specifies if symbols are recognized (the default is TRUE).

 

guint scan_binary : 1;

specifies if binary numbers are recognized (the default is FALSE).

 

guint scan_octal : 1;

specifies if octal numbers are recognized (the default is TRUE).

 

guint scan_float : 1;

specifies if floating point numbers are recognized (the default is TRUE).

 

guint scan_hex : 1;

specifies if hexadecimal numbers are recognized (the default is TRUE).

 

guint scan_hex_dollar : 1;

specifies if '$' is recognized as a prefix for hexadecimal numbers (the default is FALSE).

 

guint scan_string_sq : 1;

specifies if strings can be enclosed in single quotes (the default is TRUE).

 

guint scan_string_dq : 1;

specifies if strings can be enclosed in double quotes (the default is TRUE).

 

guint numbers_2_int : 1;

specifies if binary, octal and hexadecimal numbers are reported as G_TOKEN_INT (the default is TRUE).

 

guint int_2_float : 1;

specifies if all numbers are reported as G_TOKEN_FLOAT (the default is FALSE).

 

guint identifier_2_string : 1;

specifies if identifiers are reported as strings (the default is FALSE).

 

guint char_2_token : 1;

specifies if characters are reported by setting token = ch or as G_TOKEN_CHAR (the default is TRUE).

 

guint symbol_2_token : 1;

specifies if symbols are reported by setting token = v_symbol or as G_TOKEN_SYMBOL (the default is FALSE).

 

guint scope_0_fallback : 1;

specifies if a symbol is searched for in the default scope in addition to the current scope (the default is FALSE).

 

guint store_int64 : 1;

use value.v_int64 rather than v_int

 

G_CSET_a_2_z

#define G_CSET_a_2_z "abcdefghijklmnopqrstuvwxyz"

The set of lowercase ASCII alphabet characters. Used for specifying valid identifier characters in GScannerConfig.


G_CSET_A_2_Z

#define G_CSET_A_2_Z "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

The set of uppercase ASCII alphabet characters. Used for specifying valid identifier characters in GScannerConfig.


G_CSET_DIGITS

#define G_CSET_DIGITS "0123456789"

The set of ASCII digits. Used for specifying valid identifier characters in GScannerConfig.


G_CSET_LATINC

#define             G_CSET_LATINC

The set of uppercase ISO 8859-1 alphabet characters which are not ASCII characters. Used for specifying valid identifier characters in GScannerConfig.


G_CSET_LATINS

#define             G_CSET_LATINS

The set of lowercase ISO 8859-1 alphabet characters which are not ASCII characters. Used for specifying valid identifier characters in GScannerConfig.


enum GTokenType

The possible types of token returned from each g_scanner_get_next_token() call.

Members

G_TOKEN_EOF

the end of the file

 

G_TOKEN_LEFT_PAREN

a '(' character

 

G_TOKEN_RIGHT_PAREN

a ')' character

 

G_TOKEN_LEFT_CURLY

a '{' character

 

G_TOKEN_RIGHT_CURLY

a '}' character

 

G_TOKEN_LEFT_BRACE

a '[' character

 

G_TOKEN_RIGHT_BRACE

a ']' character

 

G_TOKEN_EQUAL_SIGN

a '=' character

 

G_TOKEN_COMMA

a ',' character

 

G_TOKEN_NONE

not a token

 

G_TOKEN_ERROR

an error occurred

 

G_TOKEN_CHAR

a character

 

G_TOKEN_BINARY

a binary integer

 

G_TOKEN_OCTAL

an octal integer

 

G_TOKEN_INT

an integer

 

G_TOKEN_HEX

a hex integer

 

G_TOKEN_FLOAT

a floating point number

 

G_TOKEN_STRING

a string

 

G_TOKEN_SYMBOL

a symbol

 

G_TOKEN_IDENTIFIER

an identifier

 

G_TOKEN_IDENTIFIER_NULL

a null identifier

 

G_TOKEN_COMMENT_SINGLE

one line comment

 

G_TOKEN_COMMENT_MULTI

multi line comment

 

union GTokenValue

A union holding the value of the token.

Members

gpointer v_symbol;

token symbol value

 

gchar *v_identifier;

token identifier value

 

gulong v_binary;

token binary integer value

 

gulong v_octal;

octal integer value

 

gulong v_int;

integer value

 

guint64 v_int64;

64-bit integer value

 

gdouble v_float;

floating point value

 

gulong v_hex;

hex integer value

 

gchar *v_string;

string value

 

gchar *v_comment;

comment value

 

guchar v_char;

character value

 

guint v_error;

error value

 

enum GErrorType

The possible errors, used in the v_error field of GTokenValue, when the token is a G_TOKEN_ERROR.

Members

G_ERR_UNKNOWN

unknown error

 

G_ERR_UNEXP_EOF

unexpected end of file

 

G_ERR_UNEXP_EOF_IN_STRING

unterminated string constant

 

G_ERR_UNEXP_EOF_IN_COMMENT

unterminated comment

 

G_ERR_NON_DIGIT_IN_CONST

non-digit character in a number

 

G_ERR_DIGIT_RADIX

digit beyond radix in a number

 

G_ERR_FLOAT_RADIX

non-decimal floating point number

 

G_ERR_FLOAT_MALFORMED

malformed floating point number