using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Text;
#if NET461 || NETSTANDARD2_0
using Npgsql.Util;
#endif
namespace Npgsql
{
class SqlQueryParser
{
readonly Dictionary _paramIndexMap = new Dictionary();
readonly StringBuilder _rewrittenSql = new StringBuilder();
internal bool StandardConformingStrings { get; set; } = true;
List _statements = default!;
NpgsqlStatement _statement = default!;
int _statementIndex;
///
/// Receives a raw SQL query as passed in by the user, and performs some processing necessary
/// before sending to the backend.
/// This includes doing parameter placeholder processing (@p => $1), and splitting the query
/// up by semicolons if needed (SELECT 1; SELECT 2)
///
/// Raw user-provided query.
/// The parameters configured on the of this query
/// or an empty if deriveParameters is set to true.
/// An empty list to be populated with the statements parsed by this method
/// A bool indicating whether parameters contains a list of preconfigured parameters or an empty list to be filled with derived parameters.
internal void ParseRawQuery(string sql, NpgsqlParameterCollection parameters, List statements, bool deriveParameters = false)
=> ParseRawQuery(sql.AsSpan(), parameters, statements, deriveParameters);
void ParseRawQuery(ReadOnlySpan sql, NpgsqlParameterCollection parameters, List statements, bool deriveParameters)
{
Debug.Assert(deriveParameters == false || parameters.Count == 0);
_statements = statements;
_statementIndex = -1;
MoveToNextStatement();
var currCharOfs = 0;
var end = sql.Length;
var ch = '\0';
int dollarTagStart;
int dollarTagEnd;
var currTokenBeg = 0;
var blockCommentLevel = 0;
var parenthesisLevel = 0;
None:
if (currCharOfs >= end)
goto Finish;
var lastChar = ch;
ch = sql[currCharOfs++];
NoneContinue:
for (; ; lastChar = ch, ch = sql[currCharOfs++])
{
switch (ch)
{
case '/':
goto BlockCommentBegin;
case '-':
goto LineCommentBegin;
case '\'':
if (StandardConformingStrings)
goto Quoted;
else
goto Escaped;
case '$':
if (!IsIdentifier(lastChar))
goto DollarQuotedStart;
else
break;
case '"':
goto DoubleQuoted;
case ':':
if (lastChar != ':')
goto ParamStart;
else
break;
case '@':
if (lastChar != '@')
goto ParamStart;
else
break;
case ';':
if (parenthesisLevel == 0)
goto SemiColon;
break;
case '(':
parenthesisLevel++;
break;
case ')':
parenthesisLevel--;
break;
case 'e':
case 'E':
if (!IsLetter(lastChar))
goto EscapedStart;
else
break;
}
if (currCharOfs >= end)
goto Finish;
}
ParamStart:
if (currCharOfs < end)
{
lastChar = ch;
ch = sql[currCharOfs];
if (IsParamNameChar(ch))
{
if (currCharOfs - 1 > currTokenBeg)
_rewrittenSql.Append(sql.Slice(currTokenBeg, currCharOfs - 1 - currTokenBeg));
currTokenBeg = currCharOfs++ - 1;
goto Param;
}
currCharOfs++;
goto NoneContinue;
}
goto Finish;
Param:
// We have already at least one character of the param name
for (;;)
{
lastChar = ch;
if (currCharOfs >= end || !IsParamNameChar(ch = sql[currCharOfs]))
{
var paramName = sql.Slice(currTokenBeg + 1, currCharOfs - (currTokenBeg + 1)).ToString();
if (!_paramIndexMap.TryGetValue(paramName, out var index))
{
// Parameter hasn't been seen before in this query
if (!parameters.TryGetValue(paramName, out var parameter))
{
if (deriveParameters)
{
parameter = new NpgsqlParameter { ParameterName = paramName };
parameters.Add(parameter);
}
else
{
// Parameter placeholder does not match a parameter on this command.
// Leave the text as it was in the SQL, it may not be a an actual placeholder
_rewrittenSql.Append(sql.Slice(currTokenBeg, currCharOfs - currTokenBeg));
currTokenBeg = currCharOfs;
if (currCharOfs >= end)
goto Finish;
currCharOfs++;
goto NoneContinue;
}
}
if (!parameter.IsInputDirection)
throw new Exception($"Parameter '{paramName}' referenced in SQL but is an out-only parameter");
_statement.InputParameters.Add(parameter);
index = _paramIndexMap[paramName] = _statement.InputParameters.Count;
}
_rewrittenSql.Append('$');
_rewrittenSql.Append(index);
currTokenBeg = currCharOfs;
if (currCharOfs >= end)
goto Finish;
currCharOfs++;
goto NoneContinue;
}
currCharOfs++;
}
Quoted:
while (currCharOfs < end)
{
if (sql[currCharOfs++] == '\'')
{
ch = '\0';
goto None;
}
}
goto Finish;
DoubleQuoted:
while (currCharOfs < end)
{
if (sql[currCharOfs++] == '"')
{
ch = '\0';
goto None;
}
}
goto Finish;
EscapedStart:
if (currCharOfs < end)
{
lastChar = ch;
ch = sql[currCharOfs++];
if (ch == '\'')
goto Escaped;
goto NoneContinue;
}
goto Finish;
Escaped:
while (currCharOfs < end)
{
ch = sql[currCharOfs++];
switch (ch)
{
case '\'':
goto MaybeConcatenatedEscaped;
case '\\':
{
if (currCharOfs >= end)
goto Finish;
currCharOfs++;
break;
}
}
}
goto Finish;
MaybeConcatenatedEscaped:
while (currCharOfs < end)
{
ch = sql[currCharOfs++];
switch (ch)
{
case '\r':
case '\n':
goto MaybeConcatenatedEscaped2;
case ' ':
case '\t':
case '\f':
continue;
default:
lastChar = '\0';
goto NoneContinue;
}
}
goto Finish;
MaybeConcatenatedEscaped2:
while (currCharOfs < end)
{
ch = sql[currCharOfs++];
switch (ch)
{
case '\'':
goto Escaped;
case '-':
{
if (currCharOfs >= end)
goto Finish;
ch = sql[currCharOfs++];
if (ch == '-')
goto MaybeConcatenatedEscapeAfterComment;
lastChar = '\0';
goto NoneContinue;
}
case ' ':
case '\t':
case '\n':
case '\r':
case '\f':
continue;
default:
lastChar = '\0';
goto NoneContinue;
}
}
goto Finish;
MaybeConcatenatedEscapeAfterComment:
while (currCharOfs < end)
{
ch = sql[currCharOfs++];
if (ch == '\r' || ch == '\n')
goto MaybeConcatenatedEscaped2;
}
goto Finish;
DollarQuotedStart:
if (currCharOfs < end)
{
ch = sql[currCharOfs];
if (ch == '$')
{
// Empty tag
dollarTagStart = dollarTagEnd = currCharOfs;
currCharOfs++;
goto DollarQuoted;
}
if (IsIdentifierStart(ch))
{
dollarTagStart = currCharOfs;
currCharOfs++;
goto DollarQuotedInFirstDelim;
}
lastChar = '$';
currCharOfs++;
goto NoneContinue;
}
goto Finish;
DollarQuotedInFirstDelim:
while (currCharOfs < end)
{
lastChar = ch;
ch = sql[currCharOfs++];
if (ch == '$')
{
dollarTagEnd = currCharOfs - 1;
goto DollarQuoted;
}
if (!IsDollarTagIdentifier(ch))
goto NoneContinue;
}
goto Finish;
DollarQuoted:
var tag = sql.Slice(dollarTagStart - 1, dollarTagEnd - dollarTagStart + 2);
var pos = sql.Slice(dollarTagEnd + 1).IndexOf(tag);
if (pos == -1)
{
currCharOfs = end;
goto Finish;
}
pos += dollarTagEnd + 1; // If the substring is found adjust the position to be relative to the entire span
currCharOfs = pos + dollarTagEnd - dollarTagStart + 2;
ch = '\0';
goto None;
LineCommentBegin:
if (currCharOfs < end)
{
ch = sql[currCharOfs++];
if (ch == '-')
goto LineComment;
lastChar = '\0';
goto NoneContinue;
}
goto Finish;
LineComment:
while (currCharOfs < end)
{
ch = sql[currCharOfs++];
if (ch == '\r' || ch == '\n')
goto None;
}
goto Finish;
BlockCommentBegin:
while (currCharOfs < end)
{
ch = sql[currCharOfs++];
if (ch == '*')
{
blockCommentLevel++;
goto BlockComment;
}
if (ch != '/')
{
if (blockCommentLevel > 0)
goto BlockComment;
lastChar = '\0';
goto NoneContinue;
}
}
goto Finish;
BlockComment:
while (currCharOfs < end)
{
ch = sql[currCharOfs++];
switch (ch)
{
case '*':
goto BlockCommentEnd;
case '/':
goto BlockCommentBegin;
}
}
goto Finish;
BlockCommentEnd:
while (currCharOfs < end)
{
ch = sql[currCharOfs++];
if (ch == '/')
{
if (--blockCommentLevel > 0)
goto BlockComment;
goto None;
}
if (ch != '*')
goto BlockComment;
}
goto Finish;
SemiColon:
_rewrittenSql.Append(sql.Slice(currTokenBeg, currCharOfs - currTokenBeg - 1));
_statement.SQL = _rewrittenSql.ToString();
while (currCharOfs < end)
{
ch = sql[currCharOfs];
if (char.IsWhiteSpace(ch))
{
currCharOfs++;
continue;
}
// TODO: Handle end of line comment? Although psql doesn't seem to handle them...
currTokenBeg = currCharOfs;
if (_rewrittenSql.Length > 0)
MoveToNextStatement();
goto None;
}
if (statements.Count > _statementIndex + 1)
statements.RemoveRange(_statementIndex + 1, statements.Count - (_statementIndex + 1));
return;
Finish:
_rewrittenSql.Append(sql.Slice(currTokenBeg, end - currTokenBeg));
_statement.SQL = _rewrittenSql.ToString();
if (statements.Count > _statementIndex + 1)
statements.RemoveRange(_statementIndex + 1, statements.Count - (_statementIndex + 1));
}
void MoveToNextStatement()
{
_statementIndex++;
if (_statements.Count > _statementIndex)
{
_statement = _statements[_statementIndex];
_statement.Reset();
}
else
{
_statement = new NpgsqlStatement();
_statements.Add(_statement);
}
_paramIndexMap.Clear();
_rewrittenSql.Clear();
}
static bool IsLetter(char ch)
=> 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z';
static bool IsIdentifierStart(char ch)
=> 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || 128 <= ch && ch <= 255;
static bool IsDollarTagIdentifier(char ch)
=> 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || '0' <= ch && ch <= '9' || ch == '_' || 128 <= ch && ch <= 255;
static bool IsIdentifier(char ch)
=> 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || '0' <= ch && ch <= '9' || ch == '_' || ch == '$' || 128 <= ch && ch <= 255;
static bool IsParamNameChar(char ch)
=> char.IsLetterOrDigit(ch) || ch == '_' || ch == '.'; // why dot??
}
}