[GROOVY-10090] Support `BlockExpression` to treat statement as expression

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Assignee: Unassigned
• Reporter: Daniel Sun
• Created: 15/May/21 20:36
• Updated: 16/May/21 19:08

Description

We need unify expression and statement by introduing BlockExpression to support new features. BlockExpression creates a new variable scope and allows yield to produce the final result, thus statement could be used where expression appears, e.g.

• GROOVY-9272 could leverage the power of this improvement to treat statement as expression.
• def v = if (pass) 'Yes' else 'No'

• def v = while(cnt < 3) {
     if (pass) yield 'Yes' // produce the value for BlockExpression (Note: default value is null)
     cnt++
  }
  

Note: we do not introduce any new syntax for BlockExpression but just introduce a new AST node

Issue Links

• Blocked: GROOVY-9272 Support switch expression