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SqlQueryParser.cs
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SqlQueryParser.cs
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using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Text;
namespace Npgsql;
sealed class SqlQueryParser
{
static NpgsqlParameterCollection EmptyParameters { get; } = new();
readonly Dictionary<string, int> _paramIndexMap = new(StringComparer.OrdinalIgnoreCase);
readonly StringBuilder _rewrittenSql = new();
/// <summary>
/// <p>
/// Receives a user SQL query as passed in by the user in <see cref="NpgsqlCommand.CommandText"/> or
/// <see cref="NpgsqlBatchCommand.CommandText"/>, and rewrites it for PostgreSQL compatibility.
/// </p>
/// <p>
/// This includes doing rewriting named parameter placeholders to positional (@p => $1), and splitting the query
/// up by semicolons (legacy batching, SELECT 1; SELECT 2).
/// </p>
/// </summary>
/// <param name="command">The user-facing <see cref="NpgsqlCommand"/> being executed.</param>
/// <param name="standardConformingStrings">Whether PostgreSQL standards-conforming are used.</param>
/// <param name="deriveParameters">
/// A bool indicating whether parameters contains a list of preconfigured parameters or an empty list to be filled with derived
/// parameters.
/// </param>
internal void ParseRawQuery(
NpgsqlCommand? command,
bool standardConformingStrings = true,
bool deriveParameters = false)
=> ParseRawQuery(command, batchCommand: null, standardConformingStrings, deriveParameters);
/// <summary>
/// <p>
/// Receives a user SQL query as passed in by the user in <see cref="NpgsqlCommand.CommandText"/> or
/// <see cref="NpgsqlBatchCommand.CommandText"/>, and rewrites it for PostgreSQL compatibility.
/// </p>
/// <p>
/// This includes doing rewriting named parameter placeholders to positional (@p => $1), and splitting the query
/// up by semicolons (legacy batching, SELECT 1; SELECT 2).
/// </p>
/// </summary>
/// <param name="batchCommand"> The user-facing <see cref="NpgsqlBatchCommand"/> being executed.</param>
/// <param name="standardConformingStrings">Whether PostgreSQL standards-conforming are used.</param>
/// <param name="deriveParameters">
/// A bool indicating whether parameters contains a list of preconfigured parameters or an empty list to be filled with derived
/// parameters.
/// </param>
internal void ParseRawQuery(
NpgsqlBatchCommand? batchCommand,
bool standardConformingStrings = true,
bool deriveParameters = false)
=> ParseRawQuery(command: null, batchCommand, standardConformingStrings, deriveParameters);
void ParseRawQuery(
NpgsqlCommand? command,
NpgsqlBatchCommand? batchCommand,
bool standardConformingStrings = true,
bool deriveParameters = false)
{
string sql;
NpgsqlParameterCollection parameters;
List<NpgsqlBatchCommand>? batchCommands;
var statementIndex = 0;
if (command is null)
{
// Batching mode. We're processing only one batch - if we encounter a semicolon (legacy batching), that's an error.
Debug.Assert(batchCommand is not null);
sql = batchCommand.CommandText;
parameters = batchCommand._parameters ?? EmptyParameters;
batchCommands = null;
}
else
{
// Command mode. Semicolons (legacy batching) may occur.
Debug.Assert(batchCommand is null);
sql = command.CommandText;
parameters = command._parameters ?? EmptyParameters;
batchCommands = command.InternalBatchCommands;
MoveToNextBatchCommand();
}
Debug.Assert(batchCommand is not null);
Debug.Assert(parameters.PlaceholderType != PlaceholderType.Positional);
Debug.Assert(deriveParameters == false || parameters.Count == 0);
// Debug.Assert(batchCommand.PositionalParameters is not null && batchCommand.PositionalParameters.Count == 0);
_paramIndexMap.Clear();
_rewrittenSql.Clear();
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:
while (true)
{
switch (ch)
{
case '/':
goto BlockCommentBegin;
case '-':
goto LineCommentBegin;
case '\'':
if (standardConformingStrings)
goto Quoted;
goto Escaped;
case '$':
if (!IsIdentifier(lastChar))
goto DollarQuotedStart;
break;
case '"':
goto Quoted;
case ':':
if (lastChar != ':')
goto NamedParamStart;
break;
case '@':
if (lastChar != '@')
goto NamedParamStart;
break;
case ';':
if (parenthesisLevel == 0)
goto SemiColon;
break;
case '(':
parenthesisLevel++;
break;
case ')':
parenthesisLevel--;
break;
case 'e':
case 'E':
if (!IsLetter(lastChar))
goto EscapedStart;
break;
}
if (currCharOfs >= end)
goto Finish;
lastChar = ch;
ch = sql[currCharOfs++];
}
NamedParamStart:
if (currCharOfs < end)
{
lastChar = ch;
ch = sql[currCharOfs];
if (IsParamNameChar(ch))
{
if (currCharOfs - 1 > currTokenBeg)
_rewrittenSql.Append(sql, currTokenBeg, currCharOfs - 1 - currTokenBeg);
currTokenBeg = currCharOfs++ - 1;
goto NamedParam;
}
currCharOfs++;
goto NoneContinue;
}
goto Finish;
NamedParam:
// We have already at least one character of the param name
while (true)
{
lastChar = ch;
if (currCharOfs >= end || !IsParamNameChar(ch = sql[currCharOfs]))
{
var paramName = sql.Substring(currTokenBeg + 1, currCharOfs - (currTokenBeg + 1));
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, currTokenBeg, currCharOfs - currTokenBeg);
currTokenBeg = currCharOfs;
if (currCharOfs >= end)
goto Finish;
currCharOfs++;
goto NoneContinue;
}
}
if (!parameter.IsInputDirection)
ThrowHelper.ThrowInvalidOperationException("Parameter '{0}' referenced in SQL but is an out-only parameter", paramName);
batchCommand.PositionalParameters.Add(parameter);
index = _paramIndexMap[paramName] = batchCommand.PositionalParameters.Count;
}
_rewrittenSql.Append('$');
_rewrittenSql.Append(index);
currTokenBeg = currCharOfs;
if (currCharOfs >= end)
goto Finish;
currCharOfs++;
goto NoneContinue;
}
currCharOfs++;
}
Quoted:
Debug.Assert(ch == '\'' || ch == '"');
while (currCharOfs < end && sql[currCharOfs] != ch)
{
currCharOfs++;
}
if (currCharOfs < end)
{
currCharOfs++;
ch = '\0';
goto None;
}
goto Finish;
EscapedStart:
if (currCharOfs < end)
{
lastChar = ch;
ch = sql[currCharOfs++];
if (ch == '\'')
goto Escaped;
goto NoneContinue;
}
goto Finish;
Escaped:
while (currCharOfs < end)
{
ch = sql[currCharOfs++];
switch (ch)
{
case '\'':
goto MaybeConcatenatedEscaped;
case '\\':
{
if (currCharOfs >= end)
goto Finish;
currCharOfs++;
break;
}
}
}
goto Finish;
MaybeConcatenatedEscaped:
while (currCharOfs < end)
{
ch = sql[currCharOfs++];
switch (ch)
{
case '\r':
case '\n':
goto MaybeConcatenatedEscaped2;
case ' ':
case '\t':
case '\f':
continue;
default:
lastChar = '\0';
goto NoneContinue;
}
}
goto Finish;
MaybeConcatenatedEscaped2:
while (currCharOfs < end)
{
ch = sql[currCharOfs++];
switch (ch)
{
case '\'':
goto Escaped;
case '-':
{
if (currCharOfs >= end)
goto Finish;
ch = sql[currCharOfs++];
if (ch == '-')
goto MaybeConcatenatedEscapeAfterComment;
lastChar = '\0';
goto NoneContinue;
}
case ' ':
case '\t':
case '\n':
case '\r':
case '\f':
continue;
default:
lastChar = '\0';
goto NoneContinue;
}
}
goto Finish;
MaybeConcatenatedEscapeAfterComment:
while (currCharOfs < end)
{
ch = sql[currCharOfs++];
if (ch == '\r' || ch == '\n')
goto MaybeConcatenatedEscaped2;
}
goto Finish;
DollarQuotedStart:
if (currCharOfs < end)
{
ch = sql[currCharOfs];
if (ch == '$')
{
// 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.AsSpan(dollarTagStart - 1, dollarTagEnd - dollarTagStart + 2);
var pos = sql.AsSpan(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 string
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, currTokenBeg, currCharOfs - currTokenBeg - 1);
batchCommand.FinalCommandText = _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...
// We've found a non-whitespace character after a semicolon - this is legacy batching.
if (command is null)
{
ThrowHelper.ThrowNotSupportedException($"Specifying multiple SQL statements in a single {nameof(NpgsqlBatchCommand)} isn't supported, " +
"please remove all semicolons.");
}
statementIndex++;
MoveToNextBatchCommand();
_paramIndexMap.Clear();
_rewrittenSql.Clear();
currTokenBeg = currCharOfs;
goto None;
}
if (batchCommands is not null && batchCommands.Count > statementIndex + 1)
batchCommands.RemoveRange(statementIndex + 1, batchCommands.Count - (statementIndex + 1));
return;
Finish:
_rewrittenSql.Append(sql, currTokenBeg, end - currTokenBeg);
if (statementIndex is 0 && _paramIndexMap.Count is 0)
// Single statement, no parameters, no rewriting necessary
batchCommand.FinalCommandText = sql;
else
batchCommand.FinalCommandText = _rewrittenSql.ToString();
if (batchCommands is not null && batchCommands.Count > statementIndex + 1)
batchCommands.RemoveRange(statementIndex + 1, batchCommands.Count - (statementIndex + 1));
void MoveToNextBatchCommand()
{
Debug.Assert(batchCommands is not null);
if (batchCommands.Count > statementIndex)
{
batchCommand = batchCommands[statementIndex];
batchCommand.Reset();
batchCommand._parameters = parameters;
}
else
{
batchCommand = new NpgsqlBatchCommand { _parameters = parameters };
batchCommands.Add(batchCommand);
}
}
}
// Is ASCII letter comparison optimization https://github.com/dotnet/runtime/blob/60cfaec2e6cffeb9a006bec4b8908ffcf71ac5b4/src/libraries/System.Private.CoreLib/src/System/Char.cs#L236
static bool IsLetter(char ch)
// [a-zA-Z]
=> (uint)((ch | 0x20) - 'a') <= ('z' - 'a');
static bool IsIdentifierStart(char ch)
// [a-zA-Z_\x80-\xFF]
=> (uint)((ch | 0x20) - 'a') <= ('z' - 'a') || ch == '_' || (uint)(ch - 128) <= 127u;
static bool IsDollarTagIdentifier(char ch)
// [a-zA-Z0-9_\x80-\xFF]
=> (uint)((ch | 0x20) - 'a') <= ('z' - 'a') || (uint)(ch - '0') <= ('9' - '0') || ch == '_' || (uint)(ch - 128) <= 127u;
static bool IsIdentifier(char ch)
// [a-zA-Z0-9_$\x80-\xFF]
=> (uint)((ch | 0x20) - 'a') <= ('z' - 'a') || (uint)(ch - '0') <= ('9' - '0') || ch == '_' || ch == '$' || (uint)(ch - 128) <= 127u;
static bool IsParamNameChar(char ch)
=> char.IsLetterOrDigit(ch) || ch == '_' || ch == '.'; // why dot??
}