ek9_insert_coalescing

Splices `LEFT <op> RIGHT` in place of a selected single-line left operand using one of the EK9 coalescing / elvis operators; answers status, edits[] (one REPLACE) and conflicts[] (kind 'selection-not-an-expression'), with a type-incompatible pairing surfacing as would-fail.

Category: Editor · Compare: no direct precedent — EK9-specific coalescing / elvis operators

When to use it

'Default name to "Anonymous" when unset' is one call with file, the LEFT operand as written (operand:'name'), operator:'?:' and rightOperand:'"Anonymous"'. Use it to wrap an existing single-line expression in one of EK9's null-safe operators (?: <? >?) without hand-writing tokens.

When not to use it

Inserting a whole new statement/expression rather than wrapping an existing operand - use ek9_insert_statements.
Adding a set-check guard to an if/while/for/switch/try head (not an inline expression) — use ek9_apply_guard_pattern.
Lifting an expression into a local rather than coalescing it — use ek9_extract_variable.

Details

The splice is syntactic but gated by a semantic scratch-compile: `?:` works on any tri-state type, while `<?`/`>?` need the operand's type to define `<=>` (`_cmp`), so a bad pairing or type-incompatible rightOperand surfaces as status:'would-fail' with the compiler diagnostic, not a broken edit. A compound left operand (e.g. `a + b`) is parenthesised for unambiguous binding, as is a compound rightOperand (`count ?: (base + 1)`) and the whole new expression when the operand sits inside another operator (`x + (a <? c)`), so the value never silently changes. The operand text names its occurrence; when it is an operand on several lines and no line is given, the call is refused naming them. A declaration's LHS is an identifier, not an expression (status:'conflicts', kind 'selection-not-an-expression') — and V1 supports a single-line left operand only.

Arguments

Argument	Type	Required	What it is
`endColumn`	integer		1-based EXCLUSIVE column of the END of the span (an IDE selection). Omit it - pass the text instead.
`file`	string	yes	Workspace-relative path to the .ek9 source file containing the expression.
`line`	integer		Optional 1-based line of the operand. Needed only when the operand text is an operand on more than one line.
`operand`	string		The LEFT operand exactly as written in the source ('name', 'a + b').
`operator`	string: ?: \| <? \| >?	yes	The coalescing operator to insert: `?:` first SET - the one that defaults an unset value ('name ?: "Anonymous"'); `<?` min, `>?` max (the LEFT operand on a tie).
`rightOperand`	string	yes	The RIGHT operand expression as source text — e.g. a fallback literal (`"Anonymous"`), another variable (`y`), or a further chained expression (`b ?: c`). Spliced verbatim.
`startColumn`	integer		1-based column of the START of the span on 'line' (an IDE selection). Omit it - pass the text instead.

It also takes the arguments every tool takes.

Recorded calls

Real calls, recorded against small projects and checked on every build - a changed answer fails it. 3 of the 10 recorded are shown.

Operand text ambiguous without line

Request

{
  "file" : "Bounds.ek9",
  "operand" : "alpha",
  "operator" : "<?",
  "rightOperand" : "beta"
}

Response

{
  "conflicts" : [ ],
  "edits" : [ ],
  "error" : {
    "message" : "operand 'alpha' is on lines [9, 10] - pass line (one of [9, 10]) to say which one to coalesce."
  },
  "meta" : {
    "serverMs" : "<timing>"
  },
  "status" : "error",
  "summary" : "operand 'alpha' is on lines [9, 10] - pass line (one of [9, 10]) to say which one to coalesce.",
  "wouldBeDiagnostics" : [ ],
  "written" : false
}

Min dry run

Request

{
  "dryRun" : true,
  "endColumn" : 23,
  "file" : "Bounds.ek9",
  "line" : 9,
  "operator" : "<?",
  "rightOperand" : "beta",
  "startColumn" : 18
}

Response

{
  "conflicts" : [ ],
  "edits" : [ {
    "after" : "      smaller <- alpha <? beta",
    "before" : "      smaller <- alpha",
    "endLine" : 9,
    "file" : "Bounds.ek9",
    "startLine" : 9,
    "type" : "replace"
  } ],
  "meta" : {
    "serverMs" : "<timing>"
  },
  "risk" : {
    "crossesModuleBoundary" : false,
    "estimatedSeverity" : "trivial",
    "fileCount" : 1,
    "lineCount" : 1,
    "touchesPublicApi" : false,
    "touchesTests" : false
  },
  "status" : "ready",
  "summary" : "Would wrap `alpha` as `alpha <? beta`",
  "workspaceHash" : "<workspace-hash>",
...

Cut short here: 3 more lines. The whole recorded call.

Right operand parenthesised

Request

{
  "dryRun" : true,
  "endColumn" : 23,
  "file" : "Bounds.ek9",
  "line" : 9,
  "operator" : "?:",
  "rightOperand" : "beta + 1",
  "startColumn" : 18
}

Response

{
  "conflicts" : [ ],
  "edits" : [ {
    "after" : "      smaller <- alpha ?: (beta + 1)",
    "before" : "      smaller <- alpha",
    "endLine" : 9,
    "file" : "Bounds.ek9",
    "startLine" : 9,
    "type" : "replace"
  } ],
  "meta" : {
    "serverMs" : "<timing>"
  },
  "risk" : {
    "crossesModuleBoundary" : false,
    "estimatedSeverity" : "trivial",
    "fileCount" : 1,
    "lineCount" : 1,
    "touchesPublicApi" : false,
    "touchesTests" : false
  },
  "status" : "ready",
  "summary" : "Would wrap `alpha` as `alpha ?: (beta + 1)`",
  "workspaceHash" : "<workspace-hash>",
...

Cut short here: 3 more lines. The whole recorded call.

When to use it

When not to use it

Details

Arguments

Recorded calls

Operand text ambiguous without line

Min dry run

Right operand parenthesised

See also