D29346: Quote and parse identifiers with square brackets

[jordi fita i mas]

jfita created this revision.
jfita added reviewers: staniek, piggz.
Herald added a project: KDb.
Herald added a subscriber: Kexi-Devel-list.
jfita requested review of this revision.

REVISION SUMMARY
  It has been decided that KDb will use the same characters to quote
  identifiers as it uses to delimit query parameters: the square
  brackets ([]). Depending on the context will decide if a quoted
  identifier is a column name or a query parameter.
  
  That is, given a table named “sample” that has two columns “id” and
  “select”, KDb is able to parse the following query
  
    SELECT [table].id AS [integer], [select], [a parameter] FROM sample [table] WHERE [select] = [another parameter] ORDER BY [integer] DESC;
  
  and can tell apart that [a parameter] and [another parameter] are query
  parameters while the rest are references to columns or column aliases.
  
  Because query parameters and quoted identifiers share the same
  characters, the lexed did not have to change much, but the parser now
  needs non-terminal identifier rule to recognize both unquoted and quoted
  identifiers. That is why i also had to change the tokens from the lexer.
  
  Most of the time the context is enough to know whether the [identifier]
  is a quoted identifier or a query parameter (e.g., in ORDER it can only
  be the former), but this can not be done for expressions and there is
  the need of a post-parse step to try to resolve the ambiguity.
  
  I first tried to create a KDbQuotedIdentifierExpression that would
  behave like a KDbVariableExpression or a KDbQueryParameterExpression
  depending on whether KDbExpression::verify would be able to find the
  name as a table column or alias.
  
  However i had a lot of trouble making it work without duplicating a lot
  of code from both KDbVariableExpression and KDbQueryParameterExpression
  and, at the end, i changed the strategy: at first, all quoted
  identifiers are assumed to be query parameters and a new
  KDbExpression::resolveQuotedIdentifiers would *replace* all query
  parameters whose value that can be resolved to a column with a new
  KDbVariableExpression.
  
  As far as i could see, Kexi picks up the changes transparently and
  stores the SQL in KDBSQL quoted with the new characters, and makes this
  change compatible with previous versions.
  
  The only drawback is that, from now own, if a query had a quoted
  identifier for a column that the user deletes now that identifiers would
  be parsed as a query parameter.
  
  Finally, i also changed the quote character in KDb::escapeIdentifier so
  that KDbNativeQueryBuilder would escape all identifiers using brackets
  instead of double quotes, otherwise they would be parsed as string
  literals instead.
  
  BUG:332161
  BUG:420599
  
  FIXED-IN:3.2.1

REPOSITORY
  R15 KDb

BRANCH
  332161-autotests

REVISION DETAIL
  https://phabricator.kde.org/D29346

AFFECTED FILES
  autotests/ExpressionsTest.cpp
  autotests/ExpressionsTest.h
  autotests/OrderByColumnTest.cpp
  autotests/parser/SqlParserTest.cpp
  autotests/parser/data/statements.txt
  autotests/tools/IdentifierTest.cpp
  src/KDb.cpp
  src/expression/KDbExpression.cpp
  src/expression/KDbExpression.h
  src/expression/KDbQueryParameterExpression.cpp
  src/parser/KDbParser_p.cpp
  src/parser/KDbSqlParser.y
  src/parser/KDbSqlScanner.l
  src/parser/generated/KDbToken.cpp
  src/parser/generated/KDbToken.h
  src/parser/generated/sqlparser.cpp
  src/parser/generated/sqlparser.h
  src/parser/generated/sqlscanner.cpp

To: jfita, staniek, piggz
Cc: Kexi-Devel-list, barman, wicik, staniek
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