Fix multiline stab clause with trailing identifier (#20)

Author: jonatanklosko

grammar.js

@@ -672,11 +672,22 @@ module.exports = grammar({
       ),
 
     _call_arguments_without_parentheses: ($) =>
-      // Right precedence, because `fun1 fun2 x, y` is `fun1(fun2(x, y))`
-      prec.right(
-        choice(
-          seq(sep1($._expression, ","), optional(seq(",", $.keywords))),
-          $.keywords
+      // In stab clauses a newline can either separate multiple body expressions
+      // or multiple stab clauses, this falls under the $.body conflict. Given a
+      // multiline stab clause with trailing identifier like `1 -> 1 \n x \n 2 -> x`,
+      // there are two matching interpretations:
+      //   * `x` as identifier and `2` as stab argument
+      //   * `x 2` call as stab argument
+      // Similarly for `Mod.fun` or `mod.fun` the newline should terminate the call.
+      // Consequently, we reject the second interpretation using dynamic precedence
+      prec.dynamic(
+        -1,
+        // Right precedence, because `fun1 fun2 x, y` is `fun1(fun2(x, y))`
+        prec.right(
+          choice(
+            seq(sep1($._expression, ","), optional(seq(",", $.keywords))),
+            $.keywords
+          )
         )
       ),
 

src/grammar.json

@@ -575,6 +575,114 @@ fun do->end
     (do_block
       (stab_clause))))
 
+
+=====================================
+stab clause / edge cases / trailing call in multiline clause
+=====================================
+
+fun do
+  1 ->
+    1
+    x
+
+  1 ->
+    1
+end
+
+fun do
+  1 ->
+    1
+    Mod.fun
+
+  1 ->
+    1
+end
+
+fun do
+  1 ->
+    1
+    mod.fun
+
+  1 ->
+    1
+end
+
+fun do
+  1 ->
+    1
+
+  x 1 ->
+    1
+end
+
+---
+
+(source
+  (call
+    (identifier)
+    (do_block
+      (stab_clause
+        (arguments
+          (integer))
+        (body
+          (integer)
+          (identifier)))
+      (stab_clause
+        (arguments
+          (integer))
+        (body
+          (integer)))))
+  (call
+    (identifier)
+    (do_block
+      (stab_clause
+        (arguments
+          (integer))
+        (body
+          (integer)
+          (call
+            (dot
+              (alias)
+              (identifier)))))
+      (stab_clause
+        (arguments
+          (integer))
+        (body
+          (integer)))))
+  (call
+    (identifier)
+    (do_block
+      (stab_clause
+        (arguments
+          (integer))
+        (body
+          (integer)
+          (call
+            (dot
+              (identifier)
+              (identifier)))))
+      (stab_clause
+        (arguments
+          (integer))
+        (body
+          (integer)))))
+  (call
+    (identifier)
+    (do_block
+      (stab_clause
+        (arguments
+          (integer))
+        (body
+          (integer)))
+      (stab_clause
+        (arguments
+          (call
+            (identifier)
+            (arguments
+              (integer))))
+        (body
+          (integer))))))
+
 =====================================
 pattern matching
 =====================================