Lexer improvements:

- Convert unquoted idents to lowercase.
- Recognize quoted idents.
- Allow all unicode whitespace characters
- Added UnexpectedSymbol token for unexpected input (otherwise it is just ignored)
- Handle mixed case keywords in the lexer file instead of filtering the stream

pglablib/PgsqlLexer.g4

@@ -1,7 +1,7 @@
 lexer grammar PgsqlLexer;
 
 @lexer::preinclude {
-#include <memory>
+#include <QString>
 }
 
 
@@ -11,21 +11,61 @@ Dot: '.';
 OpenParen: '(';
 CloseParen: ')';
 
-As: 'AS';
-By: 'BY';
-From: 'FROM';
-Full: 'FULL';
-Group: 'GROUP';
-Having: 'HAVING';
-Join: 'JOIN';
-Left : 'LEFT';
-Order : 'ORDER';
-Right : 'RIGHT';
-Select: 'SELECT';
-Where: 'WHERE';
+fragment A : 'a' | 'A';
+fragment B : 'B' | 'b';
+fragment C : 'C' | 'c';
+fragment D : 'D' | 'd';
+fragment E : 'E' | 'e';
+fragment F : 'F' | 'f';
+fragment G : 'G' | 'g';
+fragment H : 'H' | 'h';
+fragment I : 'I' | 'i';
+fragment J : 'J' | 'j';
+fragment K : 'K' | 'k';
+fragment L : 'L' | 'l';
+fragment M : 'M' | 'm';
+fragment N : 'N' | 'n';
+fragment O : 'O' | 'o';
+fragment P : 'P' | 'p';
+fragment Q : 'Q' | 'q';
+fragment R : 'R' | 'r';
+fragment S : 'S' | 's';
+fragment T : 'T' | 't';
+fragment U : 'U' | 'u';
+fragment V : 'V' | 'v';
+fragment W : 'W' | 'w';
+fragment X : 'X' | 'x';
+fragment Y : 'Y' | 'y';
+fragment Z : 'Z' | 'z';
 
-Ident: [A-Za-z_][A-Za-z_0-9]* ;             // match lower-case identifiers
+As: A S;
+By: B Y;
+From: F R O M;
+Full: F U L L;
+Group: G R O U P;
+Having: H A V I N G;
+Join: J O I N;
+Left : L E F T;
+Order : O R D E R;
+Right : R I G H T;
+Select: S E L E C T;
+Where: W H E R E;
+
+Ident: [\p{Alpha}]~[\p{White_Space}]*
+        {
+            setText(QString::fromStdString(getText()).toLower().toStdString());
+        }
+    | '"' ~["]+ '"' 
+        { 
+            {
+                std::string s = getText();
+                s = s.substr(1, s.length() - 2);
+                setText(s);
+            }
+        };
 IntegerLiteral: [1-9][0-9]*;
-StringLiteral: '\'' ('\'\'' | ~ ('\''))* '\'' { setText(getText().substr(1, getText().length()-2)); };
+StringLiteral: '\'' ('\'\'' | ~['])+ '\'' { setText(getText().substr(1, getText().length()-2)); };
 
-Whitespace : [ \t\r\n]+ -> skip ; // skip spaces, tabs, newlines
+Whitespace: [\p{White_Space}] -> skip ; // skip spaces, tabs, newlines
+
+UnexpectedSymbol: .;