scanner.h

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/*-------------------------------------------------------------------------
 *
 * scanner.h
 *      API for the core scanner (flex machine)
 *
 * The core scanner is also used by PL/pgSQL, so we provide a public API
 * for it.  However, the rest of the backend is only expected to use the
 * higher-level API provided by parser.h.
 *
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/parser/scanner.h
 *
 *-------------------------------------------------------------------------
 */
 
#ifndef SCANNER_H
#define SCANNER_H
 
#include "common/keywords.h"
 
/*
 * The scanner returns extra data about scanned tokens in this union type.
 * Note that this is a subset of the fields used in YYSTYPE of the bison
 * parsers built atop the scanner.
 */
typedef union core_YYSTYPE
{
    int         ival;           /* for integer literals */
    char       *str;            /* for identifiers and non-integer literals */
    const char *keyword;        /* canonical spelling of keywords */
} core_YYSTYPE;
 
/*
 * We track token locations in terms of byte offsets from the start of the
 * source string, not the column number/line number representation that
 * bison uses by default.  Also, to minimize overhead we track only one
 * location (usually the first token location) for each construct, not
 * the beginning and ending locations as bison does by default.  It's
 * therefore sufficient to make YYLTYPE an int.
 */
#define YYLTYPE  int
 
/*
 * Another important component of the scanner's API is the token code numbers.
 * However, those are not defined in this file, because bison insists on
 * defining them for itself.  The token codes used by the core scanner are
 * the ASCII characters plus these:
 *  %token <str>    IDENT UIDENT FCONST SCONST USCONST BCONST XCONST Op
 *  %token <ival>   ICONST PARAM
 *  %token          TYPECAST DOT_DOT COLON_EQUALS EQUALS_GREATER
 *  %token          LESS_EQUALS GREATER_EQUALS NOT_EQUALS
 * The above token definitions *must* be the first ones declared in any
 * bison parser built atop this scanner, so that they will have consistent
 * numbers assigned to them (specifically, IDENT = 258 and so on).
 */
 
/*
 * The YY_EXTRA data that a flex scanner allows us to pass around.
 * Private state needed by the core scanner goes here.  Note that the actual
 * yy_extra struct may be larger and have this as its first component, thus
 * allowing the calling parser to keep some fields of its own in YY_EXTRA.
 */
typedef struct core_yy_extra_type
{
    /*
     * The string the scanner is physically scanning.  We keep this mainly so
     * that we can cheaply compute the offset of the current token (yytext).
     */
    char       *scanbuf;
    Size        scanbuflen;
 
    /*
     * The keyword list to use, and the associated grammar token codes.
     */
    const ScanKeywordList *keywordlist;
    const uint16 *keyword_tokens;
 
    /*
     * Scanner settings to use.  These are initialized from the corresponding
     * GUC variables by scanner_init().  Callers can modify them after
     * scanner_init() if they don't want the scanner's behavior to follow the
     * prevailing GUC settings.
     */
    int         backslash_quote;
    bool        escape_string_warning;
    bool        standard_conforming_strings;
 
    /*
     * literalbuf is used to accumulate literal values when multiple rules are
     * needed to parse a single literal.  Call startlit() to reset buffer to
     * empty, addlit() to add text.  NOTE: the string in literalbuf is NOT
     * necessarily null-terminated, but there always IS room to add a trailing
     * null at offset literallen.  We store a null only when we need it.
     */
    char       *literalbuf;     /* palloc'd expandable buffer */
    int         literallen;     /* actual current string length */
    int         literalalloc;   /* current allocated buffer size */
 
    /*
     * Random assorted scanner state.
     */
    int         state_before_str_stop;  /* start cond. before end quote */
    int         xcdepth;        /* depth of nesting in slash-star comments */
    char       *dolqstart;      /* current $foo$ quote start string */
    YYLTYPE     save_yylloc;    /* one-element stack for PUSH_YYLLOC() */
 
    /* first part of UTF16 surrogate pair for Unicode escapes */
    int32       utf16_first_part;
 
    /* state variables for literal-lexing warnings */
    bool        warn_on_first_escape;
    bool        saw_non_ascii;
} core_yy_extra_type;
 
/*
 * The type of yyscanner is opaque outside scan.l.
 */
typedef void *core_yyscan_t;
 
/* Support for scanner_errposition_callback function */
typedef struct ScannerCallbackState
{
    core_yyscan_t yyscanner;
    int         location;
    ErrorContextCallback errcallback;
} ScannerCallbackState;
 
 
/* Constant data exported from parser/scan.l */
extern PGDLLIMPORT const uint16 ScanKeywordTokens[];
 
/* Entry points in parser/scan.l */
extern core_yyscan_t scanner_init(const char *str,
                                  core_yy_extra_type *yyext,
                                  const ScanKeywordList *keywordlist,
                                  const uint16 *keyword_tokens);
extern void scanner_finish(core_yyscan_t yyscanner);
extern int  core_yylex(core_YYSTYPE *yylval_param, YYLTYPE *yylloc_param,
                       core_yyscan_t yyscanner);
extern int  scanner_errposition(int location, core_yyscan_t yyscanner);
extern void setup_scanner_errposition_callback(ScannerCallbackState *scbstate,
                                               core_yyscan_t yyscanner,
                                               int location);
extern void cancel_scanner_errposition_callback(ScannerCallbackState *scbstate);
extern void scanner_yyerror(const char *message, core_yyscan_t yyscanner) pg_attribute_noreturn();
 
#endif                          /* SCANNER_H */