psqlscan.l

Go to the documentation of this file.

%top{
/*-------------------------------------------------------------------------
 *
 * psqlscan.l
 *    lexical scanner for SQL commands
 *
 * This lexer used to be part of psql, and that heritage is reflected in
 * the file name as well as function and typedef names, though it can now
 * be used by other frontend programs as well.  It's also possible to extend
 * this lexer with a compatible add-on lexer to handle program-specific
 * backslash commands.
 *
 * This code is mainly concerned with determining where the end of a SQL
 * statement is: we are looking for semicolons that are not within quotes,
 * comments, or parentheses.  The most reliable way to handle this is to
 * borrow the backend's flex lexer rules, lock, stock, and barrel.  The rules
 * below are (except for a few) the same as the backend's, but their actions
 * are just ECHO whereas the backend's actions generally do other things.
 *
 * XXX The rules in this file must be kept in sync with the backend lexer!!!
 *
 * XXX Avoid creating backtracking cases --- see the backend lexer for info.
 *
 * See psqlscan_int.h for additional commentary.
 *
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/fe_utils/psqlscan.l
 *
 *-------------------------------------------------------------------------
 */
#include "postgres_fe.h"
 
#include "common/logging.h"
#include "fe_utils/psqlscan.h"
 
#include "libpq-fe.h"
}
 
%{
 
/* LCOV_EXCL_START */
 
#include "fe_utils/psqlscan_int.h"
 
/*
 * We must have a typedef YYSTYPE for yylex's first argument, but this lexer
 * doesn't presently make use of that argument, so just declare it as int.
 */
typedef int YYSTYPE;
 
 
/* Return values from yylex() */
#define LEXRES_EOL          0   /* end of input */
#define LEXRES_SEMI         1   /* command-terminating semicolon found */
#define LEXRES_BACKSLASH    2   /* backslash command start */
 
 
#define ECHO psqlscan_emit(cur_state, yytext, yyleng)
 
%}
 
%option reentrant
%option bison-bridge
%option 8bit
%option never-interactive
%option nodefault
%option noinput
%option nounput
%option noyywrap
%option warn
%option prefix="psql_yy"
 
/*
 * Set the type of yyextra; we use it as a pointer back to the containing
 * PsqlScanState.
 */
%option extra-type="PsqlScanState"
 
/*
 * All of the following definitions and rules should exactly match
 * src/backend/parser/scan.l so far as the flex patterns are concerned.
 * The rule bodies are just ECHO as opposed to what the backend does,
 * however.  (But be sure to duplicate code that affects the lexing process,
 * such as BEGIN() and yyless().)  Also, psqlscan uses a single <<EOF>> rule
 * whereas scan.l has a separate one for each exclusive state.
 */
 
/*
 * OK, here is a short description of lex/flex rules behavior.
 * The longest pattern which matches an input string is always chosen.
 * For equal-length patterns, the first occurring in the rules list is chosen.
 * INITIAL is the starting state, to which all non-conditional rules apply.
 * Exclusive states change parsing rules while the state is active.  When in
 * an exclusive state, only those rules defined for that state apply.
 *
 * We use exclusive states for quoted strings, extended comments,
 * and to eliminate parsing troubles for numeric strings.
 * Exclusive states:
 *  <xb> bit string literal
 *  <xc> extended C-style comments
 *  <xd> delimited identifiers (double-quoted identifiers)
 *  <xh> hexadecimal byte string
 *  <xq> standard quoted strings
 *  <xqs> quote stop (detect continued strings)
 *  <xe> extended quoted strings (support backslash escape sequences)
 *  <xdolq> $foo$ quoted strings
 *  <xui> quoted identifier with Unicode escapes
 *  <xus> quoted string with Unicode escapes
 *
 * Note: we intentionally don't mimic the backend's <xeu> state; we have
 * no need to distinguish it from <xe> state, and no good way to get out
 * of it in error cases.  The backend just throws yyerror() in those
 * cases, but that's not an option here.
 */
 
%x xb
%x xc
%x xd
%x xh
%x xq
%x xqs
%x xe
%x xdolq
%x xui
%x xus
 
/*
 * In order to make the world safe for Windows and Mac clients as well as
 * Unix ones, we accept either \n or \r as a newline.  A DOS-style \r\n
 * sequence will be seen as two successive newlines, but that doesn't cause
 * any problems.  Comments that start with -- and extend to the next
 * newline are treated as equivalent to a single whitespace character.
 *
 * NOTE a fine point: if there is no newline following --, we will absorb
 * everything to the end of the input as a comment.  This is correct.  Older
 * versions of Postgres failed to recognize -- as a comment if the input
 * did not end with a newline.
 *
 * non_newline_space tracks all space characters except newlines.
 *
 * XXX if you change the set of whitespace characters, fix scanner_isspace()
 * to agree.
 */
 
space               [ \t\n\r\f\v]
non_newline_space   [ \t\f\v]
newline             [\n\r]
non_newline         [^\n\r]
 
comment         ("--"{non_newline}*)
 
whitespace      ({space}+|{comment})
 
/*
 * SQL requires at least one newline in the whitespace separating
 * string literals that are to be concatenated.  Silly, but who are we
 * to argue?  Note that {whitespace_with_newline} should not have * after
 * it, whereas {whitespace} should generally have a * after it...
 */
 
special_whitespace      ({space}+|{comment}{newline})
non_newline_whitespace  ({non_newline_space}|{comment})
whitespace_with_newline ({non_newline_whitespace}*{newline}{special_whitespace}*)
 
quote           '
/* If we see {quote} then {quotecontinue}, the quoted string continues */
quotecontinue   {whitespace_with_newline}{quote}
 
/*
 * {quotecontinuefail} is needed to avoid lexer backup when we fail to match
 * {quotecontinue}.  It might seem that this could just be {whitespace}*,
 * but if there's a dash after {whitespace_with_newline}, it must be consumed
 * to see if there's another dash --- which would start a {comment} and thus
 * allow continuation of the {quotecontinue} token.
 */
quotecontinuefail   {whitespace}*"-"?
 
/* Bit string
 * It is tempting to scan the string for only those characters
 * which are allowed. However, this leads to silently swallowed
 * characters if illegal characters are included in the string.
 * For example, if xbinside is [01] then B'ABCD' is interpreted
 * as a zero-length string, and the ABCD' is lost!
 * Better to pass the string forward and let the input routines
 * validate the contents.
 */
xbstart         [bB]{quote}
xbinside        [^']*
 
/* Hexadecimal byte string */
xhstart         [xX]{quote}
xhinside        [^']*
 
/* National character */
xnstart         [nN]{quote}
 
/* Quoted string that allows backslash escapes */
xestart         [eE]{quote}
xeinside        [^\\']+
xeescape        [\\][^0-7]
xeoctesc        [\\][0-7]{1,3}
xehexesc        [\\]x[0-9A-Fa-f]{1,2}
xeunicode       [\\](u[0-9A-Fa-f]{4}|U[0-9A-Fa-f]{8})
xeunicodefail   [\\](u[0-9A-Fa-f]{0,3}|U[0-9A-Fa-f]{0,7})
 
/* Extended quote
 * xqdouble implements embedded quote, ''''
 */
xqstart         {quote}
xqdouble        {quote}{quote}
xqinside        [^']+
 
/* $foo$ style quotes ("dollar quoting")
 * The quoted string starts with $foo$ where "foo" is an optional string
 * in the form of an identifier, except that it may not contain "$",
 * and extends to the first occurrence of an identical string.
 * There is *no* processing of the quoted text.
 *
 * {dolqfailed} is an error rule to avoid scanner backup when {dolqdelim}
 * fails to match its trailing "$".
 */
dolq_start      [A-Za-z\200-\377_]
dolq_cont       [A-Za-z\200-\377_0-9]
dolqdelim       \$({dolq_start}{dolq_cont}*)?\$
dolqfailed      \${dolq_start}{dolq_cont}*
dolqinside      [^$]+
 
/* Double quote
 * Allows embedded spaces and other special characters into identifiers.
 */
dquote          \"
xdstart         {dquote}
xdstop          {dquote}
xddouble        {dquote}{dquote}
xdinside        [^"]+
 
/* Quoted identifier with Unicode escapes */
xuistart        [uU]&{dquote}
 
/* Quoted string with Unicode escapes */
xusstart        [uU]&{quote}
 
/* error rule to avoid backup */
xufailed        [uU]&
 
 
/* C-style comments
 *
 * The "extended comment" syntax closely resembles allowable operator syntax.
 * The tricky part here is to get lex to recognize a string starting with
 * slash-star as a comment, when interpreting it as an operator would produce
 * a longer match --- remember lex will prefer a longer match!  Also, if we
 * have something like plus-slash-star, lex will think this is a 3-character
 * operator whereas we want to see it as a + operator and a comment start.
 * The solution is two-fold:
 * 1. append {op_chars}* to xcstart so that it matches as much text as
 *    {operator} would. Then the tie-breaker (first matching rule of same
 *    length) ensures xcstart wins.  We put back the extra stuff with yyless()
 *    in case it contains a star-slash that should terminate the comment.
 * 2. In the operator rule, check for slash-star within the operator, and
 *    if found throw it back with yyless().  This handles the plus-slash-star
 *    problem.
 * Dash-dash comments have similar interactions with the operator rule.
 */
xcstart         \/\*{op_chars}*
xcstop          \*+\/
xcinside        [^*/]+
 
ident_start     [A-Za-z\200-\377_]
ident_cont      [A-Za-z\200-\377_0-9\$]
 
identifier      {ident_start}{ident_cont}*
 
/* Assorted special-case operators and operator-like tokens */
typecast        "::"
dot_dot         \.\.
colon_equals    ":="
 
/*
 * These operator-like tokens (unlike the above ones) also match the {operator}
 * rule, which means that they might be overridden by a longer match if they
 * are followed by a comment start or a + or - character. Accordingly, if you
 * add to this list, you must also add corresponding code to the {operator}
 * block to return the correct token in such cases. (This is not needed in
 * psqlscan.l since the token value is ignored there.)
 */
equals_greater  "=>"
less_equals     "<="
greater_equals  ">="
less_greater    "<>"
not_equals      "!="
 
/*
 * "self" is the set of chars that should be returned as single-character
 * tokens.  "op_chars" is the set of chars that can make up "Op" tokens,
 * which can be one or more characters long (but if a single-char token
 * appears in the "self" set, it is not to be returned as an Op).  Note
 * that the sets overlap, but each has some chars that are not in the other.
 *
 * If you change either set, adjust the character lists appearing in the
 * rule for "operator"!
 */
self            [,()\[\].;\:\+\-\*\/\%\^<>\=]
op_chars        [\~\!\@\#\^\&\|\`\?\+\-\*\/\%<>\=]
operator        {op_chars}+
 
/*
 * Numbers
 *
 * Unary minus is not part of a number here.  Instead we pass it separately to
 * the parser, and there it gets coerced via doNegate().
 *
 * {numericfail} is used because we would like "1..10" to lex as 1, dot_dot, 10.
 *
 * {realfail} is added to prevent the need for scanner
 * backup when the {real} rule fails to match completely.
 */
decdigit        [0-9]
hexdigit        [0-9A-Fa-f]
octdigit        [0-7]
bindigit        [0-1]
 
decinteger      {decdigit}(_?{decdigit})*
hexinteger      0[xX](_?{hexdigit})+
octinteger      0[oO](_?{octdigit})+
bininteger      0[bB](_?{bindigit})+
 
hexfail         0[xX]_?
octfail         0[oO]_?
binfail         0[bB]_?
 
numeric         (({decinteger}\.{decinteger}?)|(\.{decinteger}))
numericfail     {decinteger}\.\.
 
real            ({decinteger}|{numeric})[Ee][-+]?{decinteger}
realfail        ({decinteger}|{numeric})[Ee][-+]
 
/* Positional parameters don't accept underscores. */
param           \${decdigit}+
 
/*
 * An identifier immediately following an integer literal is disallowed because
 * in some cases it's ambiguous what is meant: for example, 0x1234 could be
 * either a hexinteger or a decinteger "0" and an identifier "x1234".  We can
 * detect such problems by seeing if integer_junk matches a longer substring
 * than any of the XXXinteger patterns (decinteger, hexinteger, octinteger,
 * bininteger).  One "junk" pattern is sufficient because
 * {decinteger}{identifier} will match all the same strings we'd match with
 * {hexinteger}{identifier} etc.
 *
 * Note that the rule for integer_junk must appear after the ones for
 * XXXinteger to make this work correctly: 0x1234 will match both hexinteger
 * and integer_junk, and we need hexinteger to be chosen in that case.
 *
 * Also disallow strings matched by numeric_junk, real_junk and param_junk
 * for consistency.
 */
integer_junk    {decinteger}{identifier}
numeric_junk    {numeric}{identifier}
real_junk       {real}{identifier}
param_junk      \${decdigit}+{identifier}
 
/* psql-specific: characters allowed in variable names */
variable_char   [A-Za-z\200-\377_0-9]
 
other           .
 
/*
 * Dollar quoted strings are totally opaque, and no escaping is done on them.
 * Other quoted strings must allow some special characters such as single-quote
 *  and newline.
 * Embedded single-quotes are implemented both in the SQL standard
 *  style of two adjacent single quotes "''" and in the Postgres/Java style
 *  of escaped-quote "\'".
 * Other embedded escaped characters are matched explicitly and the leading
 *  backslash is dropped from the string.
 * Note that xcstart must appear before operator, as explained above!
 *  Also whitespace (comment) must appear before operator.
 */
 
%%
 
%{
        /* Declare some local variables inside yylex(), for convenience */
        PsqlScanState cur_state = yyextra;
        PQExpBuffer output_buf = cur_state->output_buf;
 
        /*
         * Force flex into the state indicated by start_state.  This has a
         * couple of purposes: it lets some of the functions below set a new
         * starting state without ugly direct access to flex variables, and it
         * allows us to transition from one flex lexer to another so that we
         * can lex different parts of the source string using separate lexers.
         */
        BEGIN(cur_state->start_state);
%}
 
{whitespace}    {
                    /*
                     * Note that the whitespace rule includes both true
                     * whitespace and single-line ("--" style) comments.
                     * We suppress whitespace until we have collected some
                     * non-whitespace data.  (This interacts with some
                     * decisions in MainLoop(); see there for details.)
                     */
                    if (output_buf->len > 0)
                        ECHO;
                }
 
{xcstart}       {
                    cur_state->xcdepth = 0;
                    BEGIN(xc);
                    /* Put back any characters past slash-star; see above */
                    yyless(2);
                    ECHO;
                }
 
<xc>{
{xcstart}       {
                    cur_state->xcdepth++;
                    /* Put back any characters past slash-star; see above */
                    yyless(2);
                    ECHO;
                }
 
{xcstop}        {
                    if (cur_state->xcdepth <= 0)
                        BEGIN(INITIAL);
                    else
                        cur_state->xcdepth--;
                    ECHO;
                }
 
{xcinside}      {
                    ECHO;
                }
 
{op_chars}      {
                    ECHO;
                }
 
\*+             {
                    ECHO;
                }
} /* <xc> */
 
{xbstart}       {
                    BEGIN(xb);
                    ECHO;
                }
<xh>{xhinside}  |
<xb>{xbinside}  {
                    ECHO;
                }
 
{xhstart}       {
                    /* Hexadecimal bit type.
                     * At some point we should simply pass the string
                     * forward to the parser and label it there.
                     * In the meantime, place a leading "x" on the string
                     * to mark it for the input routine as a hex string.
                     */
                    BEGIN(xh);
                    ECHO;
                }
 
{xnstart}       {
                    yyless(1);  /* eat only 'n' this time */
                    ECHO;
                }
 
{xqstart}       {
                    if (cur_state->std_strings)
                        BEGIN(xq);
                    else
                        BEGIN(xe);
                    ECHO;
                }
{xestart}       {
                    BEGIN(xe);
                    ECHO;
                }
{xusstart}      {
                    BEGIN(xus);
                    ECHO;
                }
 
<xb,xh,xq,xe,xus>{quote} {
                    /*
                     * When we are scanning a quoted string and see an end
                     * quote, we must look ahead for a possible continuation.
                     * If we don't see one, we know the end quote was in fact
                     * the end of the string.  To reduce the lexer table size,
                     * we use a single "xqs" state to do the lookahead for all
                     * types of strings.
                     */
                    cur_state->state_before_str_stop = YYSTATE;
                    BEGIN(xqs);
                    ECHO;
                }
<xqs>{quotecontinue} {
                    /*
                     * Found a quote continuation, so return to the in-quote
                     * state and continue scanning the literal.  Nothing is
                     * added to the literal's contents.
                     */
                    BEGIN(cur_state->state_before_str_stop);
                    ECHO;
                }
<xqs>{quotecontinuefail} |
<xqs>{other}    {
                    /*
                     * Failed to see a quote continuation.  Throw back
                     * everything after the end quote, and handle the string
                     * according to the state we were in previously.
                     */
                    yyless(0);
                    BEGIN(INITIAL);
                    /* There's nothing to echo ... */
                }
 
<xq,xe,xus>{xqdouble} {
                    ECHO;
                }
<xq,xus>{xqinside}  {
                    ECHO;
                }
<xe>{xeinside}  {
                    ECHO;
                }
<xe>{xeunicode} {
                    ECHO;
                }
<xe>{xeunicodefail} {
                    ECHO;
                }
<xe>{xeescape}  {
                    ECHO;
                }
<xe>{xeoctesc}  {
                    ECHO;
                }
<xe>{xehexesc}  {
                    ECHO;
                }
<xe>.           {
                    /* This is only needed for \ just before EOF */
                    ECHO;
                }
 
{dolqdelim}     {
                    cur_state->dolqstart = pg_strdup(yytext);
                    BEGIN(xdolq);
                    ECHO;
                }
{dolqfailed}    {
                    /* throw back all but the initial "$" */
                    yyless(1);
                    ECHO;
                }
<xdolq>{dolqdelim} {
                    if (strcmp(yytext, cur_state->dolqstart) == 0)
                    {
                        free(cur_state->dolqstart);
                        cur_state->dolqstart = NULL;
                        BEGIN(INITIAL);
                    }
                    else
                    {
                        /*
                         * When we fail to match $...$ to dolqstart, transfer
                         * the $... part to the output, but put back the final
                         * $ for rescanning.  Consider $delim$...$junk$delim$
                         */
                        yyless(yyleng - 1);
                    }
                    ECHO;
                }
<xdolq>{dolqinside} {
                    ECHO;
                }
<xdolq>{dolqfailed} {
                    ECHO;
                }
<xdolq>.        {
                    /* This is only needed for $ inside the quoted text */
                    ECHO;
                }
 
{xdstart}       {
                    BEGIN(xd);
                    ECHO;
                }
{xuistart}      {
                    BEGIN(xui);
                    ECHO;
                }
<xd>{xdstop}    {
                    BEGIN(INITIAL);
                    ECHO;
                }
<xui>{dquote}   {
                    BEGIN(INITIAL);
                    ECHO;
                }
<xd,xui>{xddouble}  {
                    ECHO;
                }
<xd,xui>{xdinside}  {
                    ECHO;
                }
 
{xufailed}  {
                    /* throw back all but the initial u/U */
                    yyless(1);
                    ECHO;
                }
 
{typecast}      {
                    ECHO;
                }
 
{dot_dot}       {
                    ECHO;
                }
 
{colon_equals}  {
                    ECHO;
                }
 
{equals_greater} {
                    ECHO;
                }
 
{less_equals}   {
                    ECHO;
                }
 
{greater_equals} {
                    ECHO;
                }
 
{less_greater}  {
                    ECHO;
                }
 
{not_equals}    {
                    ECHO;
                }
 
    /*
     * These rules are specific to psql --- they implement parenthesis
     * counting and detection of command-ending semicolon.  These must
     * appear before the {self} rule so that they take precedence over it.
     */
 
"("             {
                    cur_state->paren_depth++;
                    ECHO;
                }
 
")"             {
                    if (cur_state->paren_depth > 0)
                        cur_state->paren_depth--;
                    ECHO;
                }
 
";"             {
                    ECHO;
                    if (cur_state->paren_depth == 0 && cur_state->begin_depth == 0)
                    {
                        /* Terminate lexing temporarily */
                        cur_state->start_state = YY_START;
                        cur_state->identifier_count = 0;
                        return LEXRES_SEMI;
                    }
                }
 
    /*
     * psql-specific rules to handle backslash commands and variable
     * substitution.  We want these before {self}, also.
     */
 
"\\"[;:]        {
                    /* Force a semi-colon or colon into the query buffer */
                    psqlscan_emit(cur_state, yytext + 1, 1);
                    if (yytext[1] == ';')
                        cur_state->identifier_count = 0;
                }
 
"\\"            {
                    /* Terminate lexing temporarily */
                    cur_state->start_state = YY_START;
                    return LEXRES_BACKSLASH;
                }
 
:{variable_char}+   {
                    /* Possible psql variable substitution */
                    char       *varname;
                    char       *value;
 
                    varname = psqlscan_extract_substring(cur_state,
                                                         yytext + 1,
                                                         yyleng - 1);
                    if (cur_state->callbacks->get_variable)
                        value = cur_state->callbacks->get_variable(varname,
                                                                   PQUOTE_PLAIN,
                                                                   cur_state->cb_passthrough);
                    else
                        value = NULL;
 
                    if (value)
                    {
                        /* It is a variable, check for recursion */
                        if (psqlscan_var_is_current_source(cur_state, varname))
                        {
                            /* Recursive expansion --- don't go there */
                            pg_log_warning("skipping recursive expansion of variable \"%s\"",
                                                              varname);
                            /* Instead copy the string as is */
                            ECHO;
                        }
                        else
                        {
                            /* OK, perform substitution */
                            psqlscan_push_new_buffer(cur_state, value, varname);
                            /* yy_scan_string already made buffer active */
                        }
                        free(value);
                    }
                    else
                    {
                        /*
                         * if the variable doesn't exist we'll copy the string
                         * as is
                         */
                        ECHO;
                    }
 
                    free(varname);
                }
 
:'{variable_char}+' {
                    psqlscan_escape_variable(cur_state, yytext, yyleng,
                                             PQUOTE_SQL_LITERAL);
                }
 
:\"{variable_char}+\"   {
                    psqlscan_escape_variable(cur_state, yytext, yyleng,
                                             PQUOTE_SQL_IDENT);
                }
 
:\{\?{variable_char}+\} {
                    psqlscan_test_variable(cur_state, yytext, yyleng);
                }
 
    /*
     * These rules just avoid the need for scanner backup if one of the
     * three rules above fails to match completely.
     */
 
:'{variable_char}*  {
                    /* Throw back everything but the colon */
                    yyless(1);
                    ECHO;
                }
 
:\"{variable_char}* {
                    /* Throw back everything but the colon */
                    yyless(1);
                    ECHO;
                }
 
:\{\?{variable_char}*   {
                    /* Throw back everything but the colon */
                    yyless(1);
                    ECHO;
                }
:\{ {
                    /* Throw back everything but the colon */
                    yyless(1);
                    ECHO;
                }
 
    /*
     * Back to backend-compatible rules.
     */
 
{self}          {
                    ECHO;
                }
 
{operator}      {
                    /*
                     * Check for embedded slash-star or dash-dash; those
                     * are comment starts, so operator must stop there.
                     * Note that slash-star or dash-dash at the first
                     * character will match a prior rule, not this one.
                     */
                    int         nchars = yyleng;
                    char       *slashstar = strstr(yytext, "/*");
                    char       *dashdash = strstr(yytext, "--");
 
                    if (slashstar && dashdash)
                    {
                        /* if both appear, take the first one */
                        if (slashstar > dashdash)
                            slashstar = dashdash;
                    }
                    else if (!slashstar)
                        slashstar = dashdash;
                    if (slashstar)
                        nchars = slashstar - yytext;
 
                    /*
                     * For SQL compatibility, '+' and '-' cannot be the
                     * last char of a multi-char operator unless the operator
                     * contains chars that are not in SQL operators.
                     * The idea is to lex '=-' as two operators, but not
                     * to forbid operator names like '?-' that could not be
                     * sequences of SQL operators.
                     */
                    if (nchars > 1 &&
                        (yytext[nchars - 1] == '+' ||
                         yytext[nchars - 1] == '-'))
                    {
                        int         ic;
 
                        for (ic = nchars - 2; ic >= 0; ic--)
                        {
                            char c = yytext[ic];
                            if (c == '~' || c == '!' || c == '@' ||
                                c == '#' || c == '^' || c == '&' ||
                                c == '|' || c == '`' || c == '?' ||
                                c == '%')
                                break;
                        }
                        if (ic < 0)
                        {
                            /*
                             * didn't find a qualifying character, so remove
                             * all trailing [+-]
                             */
                            do {
                                nchars--;
                            } while (nchars > 1 &&
                                 (yytext[nchars - 1] == '+' ||
                                  yytext[nchars - 1] == '-'));
                        }
                    }
 
                    if (nchars < yyleng)
                    {
                        /* Strip the unwanted chars from the token */
                        yyless(nchars);
                    }
                    ECHO;
                }
 
{param}         {
                    ECHO;
                }
{param_junk}    {
                    ECHO;
                }
 
{decinteger}    {
                    ECHO;
                }
{hexinteger}    {
                    ECHO;
                }
{octinteger}    {
                    ECHO;
                }
{bininteger}    {
                    ECHO;
                }
{hexfail}       {
                    ECHO;
                }
{octfail}       {
                    ECHO;
                }
{binfail}       {
                    ECHO;
                }
{numeric}       {
                    ECHO;
                }
{numericfail}   {
                    /* throw back the .., and treat as integer */
                    yyless(yyleng - 2);
                    ECHO;
                }
{real}          {
                    ECHO;
                }
{realfail}      {
                    ECHO;
                }
{integer_junk}  {
                    ECHO;
                }
{numeric_junk}  {
                    ECHO;
                }
{real_junk}     {
                    ECHO;
                }
 
 
{identifier}    {
                    /*
                     * We need to track if we are inside a BEGIN .. END block
                     * in a function definition, so that semicolons contained
                     * therein don't terminate the whole statement.  Short of
                     * writing a full parser here, the following heuristic
                     * should work.  First, we track whether the beginning of
                     * the statement matches CREATE [OR REPLACE]
                     * {FUNCTION|PROCEDURE}
                     */
 
                    if (cur_state->identifier_count == 0)
                        memset(cur_state->identifiers, 0, sizeof(cur_state->identifiers));
 
                    if (pg_strcasecmp(yytext, "create") == 0 ||
                        pg_strcasecmp(yytext, "function") == 0 ||
                        pg_strcasecmp(yytext, "procedure") == 0 ||
                        pg_strcasecmp(yytext, "or") == 0 ||
                        pg_strcasecmp(yytext, "replace") == 0)
                    {
                        if (cur_state->identifier_count < sizeof(cur_state->identifiers))
                            cur_state->identifiers[cur_state->identifier_count] = pg_tolower((unsigned char) yytext[0]);
                    }
 
                    cur_state->identifier_count++;
 
                    if (cur_state->identifiers[0] == 'c' &&
                        (cur_state->identifiers[1] == 'f' || cur_state->identifiers[1] == 'p' ||
                         (cur_state->identifiers[1] == 'o' && cur_state->identifiers[2] == 'r' &&
                          (cur_state->identifiers[3] == 'f' || cur_state->identifiers[3] == 'p'))) &&
                        cur_state->paren_depth == 0)
                    {
                        if (pg_strcasecmp(yytext, "begin") == 0)
                            cur_state->begin_depth++;
                        else if (pg_strcasecmp(yytext, "case") == 0)
                        {
                            /*
                             * CASE also ends with END.  We only need to track
                             * this if we are already inside a BEGIN.
                             */
                            if (cur_state->begin_depth >= 1)
                                cur_state->begin_depth++;
                        }
                        else if (pg_strcasecmp(yytext, "end") == 0)
                        {
                            if (cur_state->begin_depth > 0)
                                cur_state->begin_depth--;
                        }
                    }
 
                    ECHO;
                }
 
{other}         {
                    ECHO;
                }
 
<<EOF>>         {
                    if (cur_state->buffer_stack == NULL)
                    {
                        cur_state->start_state = YY_START;
                        return LEXRES_EOL;      /* end of input reached */
                    }
 
                    /*
                     * We were expanding a variable, so pop the inclusion
                     * stack and keep lexing
                     */
                    psqlscan_pop_buffer_stack(cur_state);
                    psqlscan_select_top_buffer(cur_state);
                }
 
%%
 
/* LCOV_EXCL_STOP */
 
/*
 * Create a lexer working state struct.
 *
 * callbacks is a struct of function pointers that encapsulate some
 * behavior we need from the surrounding program.  This struct must
 * remain valid for the lifespan of the PsqlScanState.
 */
PsqlScanState
psql_scan_create(const PsqlScanCallbacks *callbacks)
{
    PsqlScanState state;
 
    state = (PsqlScanStateData *) pg_malloc0(sizeof(PsqlScanStateData));
 
    state->callbacks = callbacks;
 
    yylex_init(&state->scanner);
 
    yyset_extra(state, state->scanner);
 
    psql_scan_reset(state);
 
    return state;
}
 
/*
 * Destroy a lexer working state struct, releasing all resources.
 */
void
psql_scan_destroy(PsqlScanState state)
{
    psql_scan_finish(state);
 
    psql_scan_reset(state);
 
    yylex_destroy(state->scanner);
 
    free(state);
}
 
/*
 * Set the callback passthrough pointer for the lexer.
 *
 * This could have been integrated into psql_scan_create, but keeping it
 * separate allows the application to change the pointer later, which might
 * be useful.
 */
void
psql_scan_set_passthrough(PsqlScanState state, void *passthrough)
{
    state->cb_passthrough = passthrough;
}
 
/*
 * Set up to perform lexing of the given input line.
 *
 * The text at *line, extending for line_len bytes, will be scanned by
 * subsequent calls to the psql_scan routines.  psql_scan_finish should
 * be called when scanning is complete.  Note that the lexer retains
 * a pointer to the storage at *line --- this string must not be altered
 * or freed until after psql_scan_finish is called.
 *
 * encoding is the libpq identifier for the character encoding in use,
 * and std_strings says whether standard_conforming_strings is on.
 */
void
psql_scan_setup(PsqlScanState state,
                const char *line, int line_len,
                int encoding, bool std_strings)
{
    /* Mustn't be scanning already */
    Assert(state->scanbufhandle == NULL);
    Assert(state->buffer_stack == NULL);
 
    /* Do we need to hack the character set encoding? */
    state->encoding = encoding;
    state->safe_encoding = pg_valid_server_encoding_id(encoding);
 
    /* Save standard-strings flag as well */
    state->std_strings = std_strings;
 
    /* Set up flex input buffer with appropriate translation and padding */
    state->scanbufhandle = psqlscan_prepare_buffer(state, line, line_len,
                                                   &state->scanbuf);
    state->scanline = line;
 
    /* Set lookaside data in case we have to map unsafe encoding */
    state->curline = state->scanbuf;
    state->refline = state->scanline;
 
    /* Initialize state for psql_scan_get_location() */
    state->cur_line_no = 0;     /* yylex not called yet */
    state->cur_line_ptr = state->scanbuf;
}
 
/*
 * Do lexical analysis of SQL command text.
 *
 * The text previously passed to psql_scan_setup is scanned, and appended
 * (possibly with transformation) to query_buf.
 *
 * The return value indicates the condition that stopped scanning:
 *
 * PSCAN_SEMICOLON: found a command-ending semicolon.  (The semicolon is
 * transferred to query_buf.)  The command accumulated in query_buf should
 * be executed, then clear query_buf and call again to scan the remainder
 * of the line.
 *
 * PSCAN_BACKSLASH: found a backslash that starts a special command.
 * Any previous data on the line has been transferred to query_buf.
 * The caller will typically next apply a separate flex lexer to scan
 * the special command.
 *
 * PSCAN_INCOMPLETE: the end of the line was reached, but we have an
 * incomplete SQL command.  *prompt is set to the appropriate prompt type.
 *
 * PSCAN_EOL: the end of the line was reached, and there is no lexical
 * reason to consider the command incomplete.  The caller may or may not
 * choose to send it.  *prompt is set to the appropriate prompt type if
 * the caller chooses to collect more input.
 *
 * In the PSCAN_INCOMPLETE and PSCAN_EOL cases, psql_scan_finish() should
 * be called next, then the cycle may be repeated with a fresh input line.
 *
 * In all cases, *prompt is set to an appropriate prompt type code for the
 * next line-input operation.
 */
PsqlScanResult
psql_scan(PsqlScanState state,
          PQExpBuffer query_buf,
          promptStatus_t *prompt)
{
    PsqlScanResult result;
    int         lexresult;
 
    /* Must be scanning already */
    Assert(state->scanbufhandle != NULL);
 
    /* Set current output target */
    state->output_buf = query_buf;
 
    /* Set input source */
    if (state->buffer_stack != NULL)
        yy_switch_to_buffer(state->buffer_stack->buf, state->scanner);
    else
        yy_switch_to_buffer(state->scanbufhandle, state->scanner);
 
    /* And lex. */
    lexresult = yylex(NULL, state->scanner);
 
    /* Notify psql_scan_get_location() that a yylex call has been made. */
    if (state->cur_line_no == 0)
        state->cur_line_no = 1;
 
    /*
     * Check termination state and return appropriate result info.
     */
    switch (lexresult)
    {
        case LEXRES_EOL:        /* end of input */
            switch (state->start_state)
            {
                case INITIAL:
                case xqs:       /* we treat this like INITIAL */
                    if (state->paren_depth > 0)
                    {
                        result = PSCAN_INCOMPLETE;
                        *prompt = PROMPT_PAREN;
                    }
                    else if (state->begin_depth > 0)
                    {
                        result = PSCAN_INCOMPLETE;
                        *prompt = PROMPT_CONTINUE;
                    }
                    else if (query_buf->len > 0)
                    {
                        result = PSCAN_EOL;
                        *prompt = PROMPT_CONTINUE;
                    }
                    else
                    {
                        /* never bother to send an empty buffer */
                        result = PSCAN_INCOMPLETE;
                        *prompt = PROMPT_READY;
                    }
                    break;
                case xb:
                    result = PSCAN_INCOMPLETE;
                    *prompt = PROMPT_SINGLEQUOTE;
                    break;
                case xc:
                    result = PSCAN_INCOMPLETE;
                    *prompt = PROMPT_COMMENT;
                    break;
                case xd:
                    result = PSCAN_INCOMPLETE;
                    *prompt = PROMPT_DOUBLEQUOTE;
                    break;
                case xh:
                    result = PSCAN_INCOMPLETE;
                    *prompt = PROMPT_SINGLEQUOTE;
                    break;
                case xe:
                    result = PSCAN_INCOMPLETE;
                    *prompt = PROMPT_SINGLEQUOTE;
                    break;
                case xq:
                    result = PSCAN_INCOMPLETE;
                    *prompt = PROMPT_SINGLEQUOTE;
                    break;
                case xdolq:
                    result = PSCAN_INCOMPLETE;
                    *prompt = PROMPT_DOLLARQUOTE;
                    break;
                case xui:
                    result = PSCAN_INCOMPLETE;
                    *prompt = PROMPT_DOUBLEQUOTE;
                    break;
                case xus:
                    result = PSCAN_INCOMPLETE;
                    *prompt = PROMPT_SINGLEQUOTE;
                    break;
                default:
                    /* can't get here */
                    fprintf(stderr, "invalid YY_START\n");
                    exit(1);
            }
            break;
        case LEXRES_SEMI:       /* semicolon */
            result = PSCAN_SEMICOLON;
            *prompt = PROMPT_READY;
            break;
        case LEXRES_BACKSLASH:  /* backslash */
            result = PSCAN_BACKSLASH;
            *prompt = PROMPT_READY;
            break;
        default:
            /* can't get here */
            fprintf(stderr, "invalid yylex result\n");
            exit(1);
    }
 
    return result;
}
 
/*
 * Clean up after scanning a string.  This flushes any unread input and
 * releases resources (but not the PsqlScanState itself).  Note however
 * that this does not reset the lexer scan state; that can be done by
 * psql_scan_reset(), which is an orthogonal operation.
 *
 * It is legal to call this when not scanning anything (makes it easier
 * to deal with error recovery).
 */
void
psql_scan_finish(PsqlScanState state)
{
    /* Drop any incomplete variable expansions. */
    while (state->buffer_stack != NULL)
        psqlscan_pop_buffer_stack(state);
 
    /* Done with the outer scan buffer, too */
    if (state->scanbufhandle)
        yy_delete_buffer(state->scanbufhandle, state->scanner);
    state->scanbufhandle = NULL;
    if (state->scanbuf)
        free(state->scanbuf);
    state->scanbuf = NULL;
}
 
/*
 * Reset lexer scanning state to start conditions.  This is appropriate
 * for executing \r psql commands (or any other time that we discard the
 * prior contents of query_buf).  It is not, however, necessary to do this
 * when we execute and clear the buffer after getting a PSCAN_SEMICOLON or
 * PSCAN_EOL scan result, because the scan state must be INITIAL when those
 * conditions are returned.
 *
 * Note that this is unrelated to flushing unread input; that task is
 * done by psql_scan_finish().
 */
void
psql_scan_reset(PsqlScanState state)
{
    state->start_state = INITIAL;
    state->paren_depth = 0;
    state->xcdepth = 0;         /* not really necessary */
    if (state->dolqstart)
        free(state->dolqstart);
    state->dolqstart = NULL;
    state->identifier_count = 0;
    state->begin_depth = 0;
}
 
/*
 * Reselect this lexer (psqlscan.l) after using another one.
 *
 * Currently and for foreseeable uses, it's sufficient to reset to INITIAL
 * state, because we'd never switch to another lexer in a different state.
 * However, we don't want to reset e.g. paren_depth, so this can't be
 * the same as psql_scan_reset().
 *
 * Note: psql setjmp error recovery just calls psql_scan_reset(), so that
 * must be a superset of this.
 *
 * Note: it seems likely that other lexers could just assign INITIAL for
 * themselves, since that probably has the value zero in every flex-generated
 * lexer.  But let's not assume that.
 */
void
psql_scan_reselect_sql_lexer(PsqlScanState state)
{
    state->start_state = INITIAL;
}
 
/*
 * Return true if lexer is currently in an "inside quotes" state.
 *
 * This is pretty grotty but is needed to preserve the old behavior
 * that mainloop.c drops blank lines not inside quotes without even
 * echoing them.
 */
bool
psql_scan_in_quote(PsqlScanState state)
{
    return state->start_state != INITIAL &&
        state->start_state != xqs;
}
 
/*
 * Return the current scanning location (end+1 of last scanned token),
 * as a line number counted from 1 and an offset from string start.
 *
 * This considers only the outermost input string, and therefore is of
 * limited use for programs that use psqlscan_push_new_buffer().
 *
 * It would be a bit easier probably to use "%option yylineno" to count
 * lines, but the flex manual says that has a performance cost, and only
 * a minority of programs using psqlscan have need for this functionality.
 * So we implement it ourselves without adding overhead to the lexer itself.
 */
void
psql_scan_get_location(PsqlScanState state,
                       int *lineno, int *offset)
{
    const char *line_end;
 
    /*
     * We rely on flex's having stored a NUL after the current token in
     * scanbuf.  Therefore we must specially handle the state before yylex()
     * has been called, when obviously that won't have happened yet.
     */
    if (state->cur_line_no == 0)
    {
        *lineno = 1;
        *offset = 0;
        return;
    }
 
    /*
     * Advance cur_line_no/cur_line_ptr past whatever has been lexed so far.
     * Doing this prevents repeated calls from being O(N^2) for long inputs.
     */
    while ((line_end = strchr(state->cur_line_ptr, '\n')) != NULL)
    {
        state->cur_line_no++;
        state->cur_line_ptr = line_end + 1;
    }
    state->cur_line_ptr += strlen(state->cur_line_ptr);
 
    /* Report current location. */
    *lineno = state->cur_line_no;
    *offset = state->cur_line_ptr - state->scanbuf;
}
 
/*
 * Push the given string onto the stack of stuff to scan.
 *
 * NOTE SIDE EFFECT: the new buffer is made the active flex input buffer.
 */
void
psqlscan_push_new_buffer(PsqlScanState state, const char *newstr,
                         const char *varname)
{
    StackElem  *stackelem;
 
    stackelem = (StackElem *) pg_malloc(sizeof(StackElem));
 
    /*
     * In current usage, the passed varname points at the current flex input
     * buffer; we must copy it before calling psqlscan_prepare_buffer()
     * because that will change the buffer state.
     */
    stackelem->varname = varname ? pg_strdup(varname) : NULL;
 
    stackelem->buf = psqlscan_prepare_buffer(state, newstr, strlen(newstr),
                                             &stackelem->bufstring);
    state->curline = stackelem->bufstring;
    if (state->safe_encoding)
    {
        stackelem->origstring = NULL;
        state->refline = stackelem->bufstring;
    }
    else
    {
        stackelem->origstring = pg_strdup(newstr);
        state->refline = stackelem->origstring;
    }
    stackelem->next = state->buffer_stack;
    state->buffer_stack = stackelem;
}
 
/*
 * Pop the topmost buffer stack item (there must be one!)
 *
 * NB: after this, the flex input state is unspecified; caller must
 * switch to an appropriate buffer to continue lexing.
 * See psqlscan_select_top_buffer().
 */
void
psqlscan_pop_buffer_stack(PsqlScanState state)
{
    StackElem  *stackelem = state->buffer_stack;
 
    state->buffer_stack = stackelem->next;
    yy_delete_buffer(stackelem->buf, state->scanner);
    free(stackelem->bufstring);
    if (stackelem->origstring)
        free(stackelem->origstring);
    if (stackelem->varname)
        free(stackelem->varname);
    free(stackelem);
}
 
/*
 * Select the topmost surviving buffer as the active input.
 */
void
psqlscan_select_top_buffer(PsqlScanState state)
{
    StackElem  *stackelem = state->buffer_stack;
 
    if (stackelem != NULL)
    {
        yy_switch_to_buffer(stackelem->buf, state->scanner);
        state->curline = stackelem->bufstring;
        state->refline = stackelem->origstring ? stackelem->origstring : stackelem->bufstring;
    }
    else
    {
        yy_switch_to_buffer(state->scanbufhandle, state->scanner);
        state->curline = state->scanbuf;
        state->refline = state->scanline;
    }
}
 
/*
 * Check if specified variable name is the source for any string
 * currently being scanned
 */
bool
psqlscan_var_is_current_source(PsqlScanState state, const char *varname)
{
    StackElem  *stackelem;
 
    for (stackelem = state->buffer_stack;
         stackelem != NULL;
         stackelem = stackelem->next)
    {
        if (stackelem->varname && strcmp(stackelem->varname, varname) == 0)
            return true;
    }
    return false;
}
 
/*
 * Set up a flex input buffer to scan the given data.  We always make a
 * copy of the data.  If working in an unsafe encoding, the copy has
 * multibyte sequences replaced by FFs to avoid fooling the lexer rules.
 *
 * NOTE SIDE EFFECT: the new buffer is made the active flex input buffer.
 */
YY_BUFFER_STATE
psqlscan_prepare_buffer(PsqlScanState state, const char *txt, int len,
                        char **txtcopy)
{
    char       *newtxt;
 
    /* Flex wants two \0 characters after the actual data */
    newtxt = pg_malloc(len + 2);
    *txtcopy = newtxt;
    newtxt[len] = newtxt[len + 1] = YY_END_OF_BUFFER_CHAR;
 
    if (state->safe_encoding)
        memcpy(newtxt, txt, len);
    else
    {
        /* Gotta do it the hard way */
        int         i = 0;
 
        while (i < len)
        {
            int         thislen = PQmblen(txt + i, state->encoding);
 
            /* first byte should always be okay... */
            newtxt[i] = txt[i];
            i++;
            while (--thislen > 0 && i < len)
                newtxt[i++] = (char) 0xFF;
        }
    }
 
    return yy_scan_buffer(newtxt, len + 2, state->scanner);
}
 
/*
 * psqlscan_emit() --- body for ECHO macro
 *
 * NB: this must be used for ALL and ONLY the text copied from the flex
 * input data.  If you pass it something that is not part of the yytext
 * string, you are making a mistake.  Internally generated text can be
 * appended directly to state->output_buf.
 */
void
psqlscan_emit(PsqlScanState state, const char *txt, int len)
{
    PQExpBuffer output_buf = state->output_buf;
 
    if (state->safe_encoding)
        appendBinaryPQExpBuffer(output_buf, txt, len);
    else
    {
        /* Gotta do it the hard way */
        const char *reference = state->refline;
        int         i;
 
        reference += (txt - state->curline);
 
        for (i = 0; i < len; i++)
        {
            char        ch = txt[i];
 
            if (ch == (char) 0xFF)
                ch = reference[i];
            appendPQExpBufferChar(output_buf, ch);
        }
    }
}
 
/*
 * psqlscan_extract_substring --- fetch value of (part of) the current token
 *
 * This is like psqlscan_emit(), except that the data is returned as a
 * malloc'd string rather than being pushed directly to state->output_buf.
 */
char *
psqlscan_extract_substring(PsqlScanState state, const char *txt, int len)
{
    char       *result = (char *) pg_malloc(len + 1);
 
    if (state->safe_encoding)
        memcpy(result, txt, len);
    else
    {
        /* Gotta do it the hard way */
        const char *reference = state->refline;
        int         i;
 
        reference += (txt - state->curline);
 
        for (i = 0; i < len; i++)
        {
            char        ch = txt[i];
 
            if (ch == (char) 0xFF)
                ch = reference[i];
            result[i] = ch;
        }
    }
    result[len] = '\0';
    return result;
}
 
/*
 * psqlscan_escape_variable --- process :'VARIABLE' or :"VARIABLE"
 *
 * If the variable name is found, escape its value using the appropriate
 * quoting method and emit the value to output_buf.  (Since the result is
 * surely quoted, there is never any reason to rescan it.)  If we don't
 * find the variable or escaping fails, emit the token as-is.
 */
void
psqlscan_escape_variable(PsqlScanState state, const char *txt, int len,
                         PsqlScanQuoteType quote)
{
    char       *varname;
    char       *value;
 
    /* Variable lookup. */
    varname = psqlscan_extract_substring(state, txt + 2, len - 3);
    if (state->callbacks->get_variable)
        value = state->callbacks->get_variable(varname, quote,
                                               state->cb_passthrough);
    else
        value = NULL;
    free(varname);
 
    if (value)
    {
        /* Emit the suitably-escaped value */
        appendPQExpBufferStr(state->output_buf, value);
        free(value);
    }
    else
    {
        /* Emit original token as-is */
        psqlscan_emit(state, txt, len);
    }
}
 
void
psqlscan_test_variable(PsqlScanState state, const char *txt, int len)
{
    char       *varname;
    char       *value;
 
    varname = psqlscan_extract_substring(state, txt + 3, len - 4);
    if (state->callbacks->get_variable)
        value = state->callbacks->get_variable(varname, PQUOTE_PLAIN,
                                               state->cb_passthrough);
    else
        value = NULL;
    free(varname);
 
    if (value != NULL)
    {
        appendPQExpBufferStr(state->output_buf, "TRUE");
        free(value);
    }
    else
    {
        appendPQExpBufferStr(state->output_buf, "FALSE");
    }
}