fix(math-parser): add empty exponent support (#1688)

thm-mni-ii · Jul 25, 2024 · 5c5a81b · 5c5a81b
1 parent 2bec80e
commit 5c5a81b
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Showing 4 changed files with 24 additions and 1 deletion.
diff --git a/modules/fbs-core/math-parser/src/main/antlr/de/thm/ii/fbs/mathParser/Math.g4 b/modules/fbs-core/math-parser/src/main/antlr/de/thm/ii/fbs/mathParser/Math.g4
@@ -25,13 +25,14 @@ mulFactor   : expo // higher presedence!
             | mulFactor ' '* expo
             ;
 
-expo        : expo ' '* EXP ' '*  SUB? factor
+expo        : expo ' '* EXP ' '* SUB? factor
             | expo unicode_expo
             | factor
             ;
 
 factor      : LEFT? OPENING_ROUND_BRACKET ' '* expr ' '* RIGHT? CLOSING_ROUND_BRACKET
             | OPENING_CURLY_BRACKET ' '* expr ' '* CLOSING_CURLY_BRACKET
+            | EMPTY_CURLY_BRACKETS
             | (NUMBER|VAR)
             ;
 
@@ -63,6 +64,7 @@ OPENING_ROUND_BRACKET: '(';
 CLOSING_ROUND_BRACKET: ')';
 OPENING_CURLY_BRACKET: '{';
 CLOSING_CURLY_BRACKET: '}';
+EMPTY_CURLY_BRACKETS: '{}';
 OPENING_SQUARE_BRACKET: '[';
 CLOSING_SQUARE_BRACKET: ']';
 LEFT: '\\left';

diff --git a/modules/fbs-core/math-parser/src/main/kotlin/de/thm/ii/fbs/mathParser/AstBuilder.kt b/modules/fbs-core/math-parser/src/main/kotlin/de/thm/ii/fbs/mathParser/AstBuilder.kt
@@ -82,6 +82,7 @@ class AstBuilder(val eq: MathParser.EqContext) {
             factor.expr() !== null -> buildExpr(factor.expr())
             factor.NUMBER() !== null -> Num(germanFormat.parse(factor.NUMBER().text.replace("{,}", ",")))
             factor.VAR() !== null -> Var(factor.VAR().text)
+            factor.EMPTY_CURLY_BRACKETS() !== null -> Num(1)
             else -> throw IllegalArgumentException("not a legal factor: ${factor.text}")
         }
 

diff --git a/...les/fbs-core/math-parser/src/test/kotlin/de/thm/ii/fbs/mathParser/MathParserHelperTest.kt b/...les/fbs-core/math-parser/src/test/kotlin/de/thm/ii/fbs/mathParser/MathParserHelperTest.kt
@@ -465,6 +465,16 @@ internal class MathParserHelperTest {
         )
     }
 
+    @Test
+    fun parseEmptyExp() {
+        assertEquals(
+            Ast(
+                Operation(Operator.ADD, Operation(Operator.EXP, Num(2), Num(1)), Operation(Operator.EXP, Num(2), Num(1)))
+            ),
+            MathParserHelper.parse("2^{}+2^{}")
+        )
+    }
+
     @Test
     fun parseLatexRad() {
         assertEquals(

diff --git a/...bs-core/math-parser/src/test/kotlin/de/thm/ii/fbs/mathParser/SemanticAstComparatorTest.kt b/...bs-core/math-parser/src/test/kotlin/de/thm/ii/fbs/mathParser/SemanticAstComparatorTest.kt
@@ -221,4 +221,14 @@ internal class SemanticAstComparatorTest {
             )
         )
     }
+
+    @Test
+    fun emptyExponentTest() {
+        assertTrue(
+            semanticAstComparator.compare(
+                MathParserHelper.parse("a^{}"),
+                MathParserHelper.parse("a")
+            )
+        )
+    }
 }