[FLINK-7759][TableAPI & SQL] Fix Bug that fieldName with Boolean pref…

[Xpray]

Fix Bug that fieldName with Boolean prefix can't be parsed by ExpressionParser

What is the purpose of the change

Fix bug that field names with boolean prefix like "truex" or "FALSE_TARGET" can't be parsed by ExpressionParser

Brief change log

use ||| instead of | in atom parser, try to match as long as possible, and exchanging of positions of fieldReference parser and literalExpr parser is necessary, because boolean can be matched by both parsers, then it's captured by the latter one literalExpr .

Verifying this change

This change added tests and can be verified as follows:

StringExpressionTest.testFieldWithBooleanPrefix

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive):no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not documented

[fhueske]

Thanks for the PR @Xpray.
This looks good. Will merge it.

[fhueske]

I've converted the test into an expression test (extending ExpressionTestBase) and moved it to org.apache.flink.table.expressions.

[Xpray]

That's great, I should have done this.