Merge pull request #4412 from h1alexbel/4386

bug(#4386): auto named formation with `\phi` object inside

Author: yegor256

eo-parser/src/main/antlr4/org/eolang/parser/Eo.g4

@@ -128,7 +128,7 @@ void: NAME
 // - vertical
 // Ends on the next line
 application
-    : happlicationExtended onameOrTname EOL
+    : happlicationExtendedOrAphi onameOrTname EOL
     | vapplication
     ;
 
@@ -156,6 +156,20 @@ happlicationExtended
     | happlicationReversed
     ;
 
+// Application with auto-Phi formation
+onlyAphi
+    : happlicationHeadExtended happlicationTail aphi?
+    ;
+
+happlicationExtendedOrAphi
+    : happlicationExtended | onlyAphi
+    ;
+
+// Auto-Phi formation
+aphi
+    : SPACE ARROW ARROW SPACE voids
+    ;
+
 // Reversed horizontal application
 happlicationReversed
     : happlicationReversedHead happlicationTail?
@@ -269,7 +283,7 @@ vapplicationArgBound
 // Vertical application arguments with bindings
 // Ends on the current line
 vapplicationArgBoundCurrent
-    : LB happlicationExtended RB as oname? // horizontal application
+    : LB happlicationExtendedOrAphi RB as oname? // horizontal application
     | commentOptional LB hanonym RB as fname? // horizontal anonym object
     | (just | method) as oname? // just an object reference | method
     ;
@@ -292,7 +306,7 @@ vapplicationArgUnbound
 // Vertical application arguments without bindings
 // Ends on the current line
 vapplicationArgUnboundCurrent
-    : happlicationExtended oname? // horizontal application
+    : happlicationExtendedOrAphi oname? // horizontal application
     | commentOptional hanonym fname? // horizontal anonym object
     | (just | method) oname? // just an object reference or method
     ;

eo-parser/src/main/java/org/eolang/parser/AutoName.java

@@ -0,0 +1,39 @@
+/*
+ * SPDX-FileCopyrightText: Copyright (c) 2016-2025 Objectionary.com
+ * SPDX-License-Identifier: MIT
+ */
+package org.eolang.parser;
+
+import org.antlr.v4.runtime.ParserRuleContext;
+import org.cactoos.Text;
+
+/**
+ * Auto name for abstract object.
+ * @since 0.57.4
+ */
+final class AutoName implements Text {
+
+    /**
+     * The line number.
+     */
+    private final int line;
+
+    /**
+     * The Position in line.
+     */
+    private final int position;
+
+    AutoName(final ParserRuleContext context) {
+        this(context.getStart().getLine(), context.getStart().getCharPositionInLine());
+    }
+
+    AutoName(final int lne, final int pos) {
+        this.line = lne;
+        this.position = pos;
+    }
+
+    @Override
+    public String asString() {
+        return String.format("a\uD83C\uDF35%d%d", this.line, this.position);
+    }
+}

eo-parser/src/main/java/org/eolang/parser/XeEoListener.java

@@ -371,6 +371,42 @@ public void exitHapplicationExtended(final EoParser.HapplicationExtendedContext
         // Nothing here
     }
 
+    @Override
+    public void enterOnlyAphi(final EoParser.OnlyAphiContext ctx) {
+        this.startAbstract(ctx)
+            .enter().prop("name", new AutoName(ctx).asString())
+            .start(ctx)
+            .prop(
+                "base", String.format("$.%s", ctx.happlicationHeadExtended().getText())
+            )
+            .prop("name", "@");
+    }
+
+    @Override
+    public void exitOnlyAphi(final EoParser.OnlyAphiContext ctx) {
+        // Nothing here
+    }
+
+    @Override
+    public void enterHapplicationExtendedOrAphi(final EoParser.HapplicationExtendedOrAphiContext ctx) {
+        // Nothing here
+    }
+
+    @Override
+    public void exitHapplicationExtendedOrAphi(final EoParser.HapplicationExtendedOrAphiContext ctx) {
+        // Nothing here
+    }
+
+    @Override
+    public void enterAphi(final EoParser.AphiContext ctx) {
+        // Nothing here
+    }
+
+    @Override
+    public void exitAphi(final EoParser.AphiContext ctx) {
+        // Nothing here
+    }
+
     @Override
     public void enterHapplicationReversed(final EoParser.HapplicationReversedContext ctx) {
         // Nothing here

eo-parser/src/test/resources/org/eolang/parser/eo-syntax/auto-phi-formation.yaml

@@ -0,0 +1,18 @@
+# SPDX-FileCopyrightText: Copyright (c) 2016-2025 Objectionary.com
+# SPDX-License-Identifier: MIT
+---
+# yamllint disable rule:line-length
+sheets: []
+asserts:
+  - /object[not(errors)]
+  - //o[not(@base) and @name='a🌵78' and o[@name='@']]
+  - //o[not(@base) and @name='a🌵88' and o[@name='@']]
+input: |
+  # No comments.
+  [n] > app
+    malloc.of > @
+      8
+      [m]
+        while > @
+          m.get.eq 42 >> [i]
+          m.put 42 >> [i]

eo-parser/src/test/resources/org/eolang/parser/eo-typos/auto-phi-in-test-attributes.yaml

@@ -0,0 +1,14 @@
+# SPDX-FileCopyrightText: Copyright (c) 2016-2025 Objectionary.com
+# SPDX-License-Identifier: MIT
+---
+# yamllint disable rule:line-length
+line: 4
+message: |-
+  [4:19] error: 'Invalid object declaration'
+      5.plus 5 >> [] +> test
+                     ^
+input: |-
+  # No comments.
+  [] > x
+    start > @
+      5.plus 5 >> [] +> test