added support for exponent notation to the tokens LONG and DOUBLE

README-X.md

@@ -250,8 +250,8 @@ available:
 | Literal True  | true                        | A positive boolean value             |
 | Literal False | false                       | A negative boolean value             |
 | Literal Null  | null                        | The null value                       |
-| Double        | 12.3, .4, -.8, -1           | A non-whole number                   |
-| Long          | 123, 4, -8, -1              | A whole number                       |
+| Double        | 12.3, .4, -.8, -1, .5e-4    | A non-whole number                   |
+| Long          | 123, 4, -8, -1, 2e3         | A whole number                       |
 | String        | "my string", "my \\" quote" | An immediate string of characters    |
 | Identifier    | a, my_var, my_func          | Either a variable or a function name |
 

README.md

@@ -807,8 +807,8 @@ available:
 | Literal True  | true                        | A positive boolean value             |
 | Literal False | false                       | A negative boolean value             |
 | Literal Null  | null                        | The null value                       |
-| Double        | 12.3, .4, -.8, -1           | A non-whole number                   |
-| Long          | 123, 4, -8, -1              | A whole number                       |
+| Double        | 12.3, .4, -.8, -1, .5e-4    | A non-whole number                   |
+| Long          | 123, 4, -8, -1, 2e3         | A whole number                       |
 | String        | "my string", "my \\" quote" | An immediate string of characters    |
 | Identifier    | a, my_var, my_func          | Either a variable or a function name |
 
@@ -823,8 +823,8 @@ The following *EBNF* describes the grammar of this small expression language pre
 Digit ::= [0-9]
 Letter ::= [A-Za-z]
 
-Long ::= "-"? Digit+
-Double ::= "-"? Digit* "." Digit+
+Long ::= "-"? Digit+ ("e" Digit+)?
+Double ::= "-"? Digit* "." Digit+ ("e" "-"? Digit+)?
 String ::= '"' ('\"' | [^"] | "\s")* '"'
 Identifier ::= Letter (Digit | Letter | '_')*
 Literal ::= "true" | "false" | "null"

src/main/java/me/blvckbytes/gpeee/error/NegativeExponentOnLongError.java

@@ -0,0 +1,32 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2023 BlvckBytes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package me.blvckbytes.gpeee.error;
+
+public class NegativeExponentOnLongError extends AEvaluatorError {
+
+  public NegativeExponentOnLongError(int row, int col, String rawInput) {
+    super(row, col, rawInput, "A negative exponent is not allowed on a long, please use a double instead!");
+  }
+}

src/main/java/me/blvckbytes/gpeee/parser/Parser.java

@@ -563,7 +563,7 @@ private AExpression parsePrimaryExpression(ITokenizer tokenizer) throws AEvaluat
     switch (tk.getType()) {
       case LONG:
         logger.log(Level.FINEST, () -> DebugLogSource.PARSER + "Found an integer");
-        return new LongExpression(Integer.parseInt(tk.getValue()), tk, tk, tokenizer.getRawText());
+        return new LongExpression(parseIntegerWithPossibleExponent(tk), tk, tk, tokenizer.getRawText());
 
       case DOUBLE:
         logger.log(Level.FINEST, () -> DebugLogSource.PARSER + "Found a double");
@@ -740,4 +740,26 @@ else if (rhsPrecedence == PrecedenceMode.RESET)
 
     return lhs;
   }
+
+  /**
+   * Parses an integer token which supports exponent notation, which java does not (only on doubles).
+   * @param tk Token of integer type
+   * @return Value represented by the token
+   */
+  private int parseIntegerWithPossibleExponent(Token tk) {
+    String tokenValue = tk.getValue();
+    int exponentIndicatorIndex = tokenValue.indexOf('e');
+
+    int number;
+
+    if (exponentIndicatorIndex < 0)
+      number = Integer.parseInt(tokenValue);
+    else {
+      int numberValue = Integer.parseInt(tokenValue.substring(0, exponentIndicatorIndex));
+      int exponentValue = Integer.parseInt(tokenValue.substring(exponentIndicatorIndex + 1));
+      number = numberValue * (int) Math.pow(10, exponentValue);
+    }
+
+    return number;
+  }
 }

src/main/java/me/blvckbytes/gpeee/tokenizer/TokenType.java

@@ -24,6 +24,7 @@
 
 package me.blvckbytes.gpeee.tokenizer;
 
+import me.blvckbytes.gpeee.error.NegativeExponentOnLongError;
 import me.blvckbytes.gpeee.error.UnterminatedStringError;
 import org.jetbrains.annotations.Nullable;
 
@@ -63,17 +64,19 @@ public enum TokenType {
     return result.toString();
   }),
 
-  // -?[0-9]+
+  // -?[0-9]+(e[0-9]+)?
   LONG(TokenCategory.VALUE, null, tokenizer -> {
     StringBuilder result = new StringBuilder();
 
     if (collectDigits(tokenizer, result, false) != CollectorResult.READ_OKAY)
       return null;
 
+    possiblyCollectExponent(tokenizer, result, false);
+
     return result.toString();
   }),
 
-  // -?[0-9]*.?[0-9]+
+  // -?[0-9]*.?[0-9]+(e-?[0-9]+)?
   DOUBLE(TokenCategory.VALUE, null, tokenizer -> {
     StringBuilder result = new StringBuilder();
 
@@ -103,6 +106,8 @@ public enum TokenType {
     if (collectDigits(tokenizer, result, false) != CollectorResult.READ_OKAY)
       return null;
 
+    possiblyCollectExponent(tokenizer, result, true);
+
     return result.toString();
   }),
 
@@ -270,6 +275,48 @@ public FTokenReader getTokenReader() {
     return tokenReader;
   }
 
+  private static void possiblyCollectExponent(ITokenizer tokenizer, StringBuilder result, boolean allowNegativeExponent) {
+    if (!tokenizer.hasNextChar() || tokenizer.peekNextChar() != 'e')
+      return;
+
+    // It could occur that an 'e' immediately follows a long or double but is not meant as an exponent.
+    // If parsing the exponent number is not successful, these characters are to be put back, as they likely
+    // carry another meaning. The initial number should still be parsed though, so a failure would not be appropriate.
+    tokenizer.saveState(true);
+
+    // Append 'e'
+    result.append(tokenizer.nextChar());
+
+    boolean hasNegativeSign = false;
+    int negativeSignRow = tokenizer.getCurrentRow();
+    int negativeSignCol = tokenizer.getCurrentCol();
+
+    // Allow a negative sign in the exponent, which is usually taken care of by the minus token for all numbers
+    if (tokenizer.hasNextChar() && tokenizer.peekNextChar() == '-') {
+      hasNegativeSign = true;
+      result.append(tokenizer.nextChar());
+    }
+
+    // Collect exponent digits
+    if (collectDigits(tokenizer, result, false) == CollectorResult.READ_OKAY) {
+      if (!allowNegativeExponent && hasNegativeSign)
+        throw new NegativeExponentOnLongError(negativeSignRow, negativeSignCol, tokenizer.getRawText());
+
+      tokenizer.discardState(true);
+      return;
+    }
+
+    // Was likely not meant as an exponent
+    tokenizer.restoreState(true);
+
+    // Remove the '-' again
+    if (hasNegativeSign)
+      result.deleteCharAt(result.length() - 1);
+
+    // Remove the 'e' again
+    result.deleteCharAt(result.length() - 1);
+  }
+
   private static CollectorResult collectDigits(ITokenizer tokenizer, StringBuilder result, boolean stopBeforeDot) {
     if (!tokenizer.hasNextChar())
       return CollectorResult.NO_NEXT_CHAR;

src/main/resources/grammar.ebnf

@@ -1,8 +1,8 @@
 Digit ::= [0-9]
 Letter ::= [A-Za-z]
 
-Long ::= "-"? Digit+
-Double ::= "-"? Digit* "." Digit+
+Long ::= "-"? Digit+ ("e" Digit+)?
+Double ::= "-"? Digit* "." Digit+ ("e" "-"? Digit+)?
 String ::= '"' ('\"' | [^"] | "\s")* '"'
 Identifier ::= Letter (Digit | Letter | '_')*
 Literal ::= "true" | "false" | "null"

src/test/java/me/blvckbytes/gpeee/TerminalTests.java

@@ -40,10 +40,18 @@ public void shouldEvaluateTerminals() {
       validator.validate(".3", .3);
       validator.validate("-3", -3);
       validator.validateThrows("-3a", UndefinedVariableError.class);
+      validator.validateThrows("3e", UndefinedVariableError.class);
+      validator.validate("3e3", 3 * (int) Math.pow(10, 3));
+      validator.validate("-3e3", -3 * (int) Math.pow(10, 3));
+      validator.validateThrows("3e-3", NegativeExponentOnLongError.class);
 
       // Double
       validator.validate("3.3", 3.3);
       validator.validate("-3.3", -3.3);
+      validator.validateThrows("3.3e", UndefinedVariableError.class);
+      validator.validate("3.3e3", 3.3 * Math.pow(10, 3));
+      validator.validate("-3.3e3", -3.3 * Math.pow(10, 3));
+      validator.validate("-3.3e-3", -3.3 * Math.pow(10, -3));
 
       // Would be parsed as a member access of the member .3 on 3
       validator.validateThrows("3..3", UnknownMemberError.class);