feat: value converter for strings & ints (#655)

### Summary of Changes

Add conversion for ints and strings, including proper handling of escape
sequences.

---------

Co-authored-by: megalinter-bot <129584137+megalinter-bot@users.noreply.github.com>

Author: lars-reimann

docs/language/pipeline-language/expressions.md

@@ -23,16 +23,18 @@ String literals describe text. Their syntax is simply text enclosed by double qu
 
 | Escape sequence | Meaning                                                              |
 |-----------------|----------------------------------------------------------------------|
-| `#!sds \b`      | Backspace                                                            |
-| `#!sds \t`      | Tab                                                                  |
-| `#!sds \n`      | New line                                                             |
-| `#!sds \f`      | Form feed                                                            |
-| `#!sds \r`      | Carriage return                                                      |
-| `#!sds \"`      | Double quote                                                         |
-| `#!sds \'`      | Single quote                                                         |
-| `#!sds \\`      | Backslash                                                            |
-| `#!sds \{`      | Opening curly brace (used for [template strings](#template-strings)) |
-| `#!sds \uXXXX`  | Unicode character, where `#!sds XXXX` is its hexadecimal index       |
+| `\b`            | Backspace                                                            |
+| `\f`            | Form feed                                                            |
+| `\n`            | New line                                                             |
+| `\r`            | Carriage return                                                      |
+| `\t`            | Tab                                                                  |
+| `\v`            | Vertical tab                                                         |
+| `\0`            | Null character                                                       |
+| `\'`            | Single quote                                                         |
+| `\"`            | Double quote                                                         |
+| `\{`            | Opening curly brace (used for [template strings](#template-strings)) |
+| `\\`            | Backslash                                                            |
+| `\uXXXX`        | Unicode character, where `XXXX` is its hexadecimal code              |
 
 String literals can contain also contain raw line breaks:
 
@@ -134,7 +136,7 @@ nullableExpression ?: 42
 
 The syntax for template strings is similar to [string literals](#string-literals): They are also delimited by double quotes, the text can contain escape sequences, and raw newlines can be inserted. The additional syntax are _template expressions_, which are any expression enclosed by `#!sds {{` and `#!sds }}`. There must be no space between the curly braces.
 
-These template expressions are evaluated, converted to a string and inserted into the template string at their position. The template string in the example above is, hence, equivalent to the [string literal](#string-literals) "1 + 2 = 3".
+These template expressions are evaluated, converted to a string and inserted into the template string at their position. The template string in the example above is, hence, equivalent to the [string literal](#string-literals) `#!sds "1 + 2 = 3"`.
 
 ## References
 

esbuild.mjs

@@ -50,7 +50,7 @@ const ctx = await esbuild.context({
     entryPoints: ['src/cli/main.ts', 'src/extension/main.ts', 'src/language/main.ts'],
     outdir: 'out',
     bundle: true,
-    target: 'ES2017',
+    target: 'ES2020',
     // VSCode's extension host is still using cjs, so we need to transform the code
     format: 'cjs',
     // To prevent confusing node, we explicitly use the `.cjs` extension

language-configuration.json

@@ -16,7 +16,7 @@
         { "open": "\"", "close": "\"", "notIn": ["string", "comment"] },
         { "open": "`", "close": "`", "notIn": ["string", "comment"] },
         { "open": "»", "close": "«", "notIn": ["string", "comment"] },
-        { "open": "/*", "close": " */", "notIn": ["string"] }
+        { "open": "/*", "close": " */", "notIn": ["string", "comment"] }
     ],
     "surroundingPairs": [
         ["(", ")"],

src/language/grammar/safe-ds-value-converter.ts

@@ -1,18 +1,77 @@
-import { convertString, CstNode, DefaultValueConverter, GrammarAST, ValueType } from 'langium';
+import { convertBigint, CstNode, DefaultValueConverter, GrammarAST, ValueType } from 'langium';
 
 export class SafeDsValueConverter extends DefaultValueConverter {
     protected override runConverter(rule: GrammarAST.AbstractRule, input: string, cstNode: CstNode): ValueType {
         switch (rule.name.toUpperCase()) {
             case 'ID':
                 return input.replaceAll('`', '');
+            case 'INT':
+                return convertBigint(input);
+            case 'STRING':
+                return convertString(input, 1, 1);
             case 'TEMPLATE_STRING_START':
-                return convertString(input.substring(0, input.length - 1));
+                return convertString(input, 1, 2);
             case 'TEMPLATE_STRING_INNER':
-                return convertString(input.substring(1, input.length - 1));
+                return convertString(input, 2, 2);
             case 'TEMPLATE_STRING_END':
-                return convertString(input.substring(1));
+                return convertString(input, 2, 1);
             default:
                 return super.runConverter(rule, input, cstNode);
         }
     }
 }
+
+const convertString = (input: string, openingDelimiterLength: number, closingDelimiterLength: number): string => {
+    let result = '';
+    const endIndex = input.length - 1 - closingDelimiterLength;
+
+    for (let i = openingDelimiterLength; i <= endIndex; i++) {
+        const current = input.charAt(i);
+        if (current === '\\' && i < endIndex) {
+            const [stringToAdd, newIndex] = handleEscapeSequence(input, i + 1, endIndex);
+            result += stringToAdd;
+            i = newIndex - 1; // -1 because the loop will increment it
+        } else {
+            result += current;
+        }
+    }
+
+    return result;
+};
+
+/**
+ * Handle an escape sequence.
+ *
+ * @param input The entire input string.
+ * @param index The index of the escape sequence (after the slash).
+ * @param endIndex The index of the last character of the input string, excluding delimiters.
+ * @returns An array containing the string to add to the result and the new index.
+ */
+const handleEscapeSequence = (input: string, index: number, endIndex: number): [string, number] => {
+    const current = input.charAt(index);
+    switch (current) {
+        case 'b':
+            return ['\b', index + 1];
+        case 'f':
+            return ['\f', index + 1];
+        case 'n':
+            return ['\n', index + 1];
+        case 'r':
+            return ['\r', index + 1];
+        case 't':
+            return ['\t', index + 1];
+        case 'v':
+            return ['\v', index + 1];
+        case '0':
+            return ['\0', index + 1];
+    }
+
+    if (current === 'u' && index + 4 <= endIndex) {
+        const code = input.substring(index + 1, index + 5);
+        if (code.match(/[0-9a-fA-F]{4}/gu)) {
+            return [String.fromCharCode(parseInt(code, 16)), index + 5];
+        }
+    }
+
+    return [current, index + 1];
+};

src/language/grammar/safe-ds.langium

@@ -766,7 +766,7 @@ SdsFloat returns SdsFloat:
 ;
 
 interface SdsInt extends SdsNumber {
-    value: number
+    value: bigint
 }
 
 SdsInt returns SdsInt:
@@ -1069,7 +1069,7 @@ terminal FLOAT returns number
     | DECIMAL_DIGIT+ FLOAT_EXPONENT;
 terminal fragment DECIMAL_DIGIT: /[0-9]/;
 terminal fragment FLOAT_EXPONENT: ('e' | 'E' )('+' | '-' )? DECIMAL_DIGIT+;
-terminal INT returns number: DECIMAL_DIGIT+;
+terminal INT returns bigint: DECIMAL_DIGIT+;
 terminal STRING returns string: STRING_START STRING_TEXT* STRING_END;
 terminal fragment STRING_START: STRING_DELIMITER;
 terminal fragment STRING_END: '{'? STRING_DELIMITER;

src/language/partialEvaluation/safe-ds-partial-evaluator.ts

@@ -100,7 +100,7 @@ export class SafeDsPartialEvaluator {
         } else if (isSdsFloat(node)) {
             return new FloatConstant(node.value);
         } else if (isSdsInt(node)) {
-            return new IntConstant(BigInt(node.value));
+            return new IntConstant(node.value);
         } else if (isSdsNull(node)) {
             return NullConstant;
         } else if (isSdsString(node)) {
@@ -520,4 +520,4 @@ export class SafeDsPartialEvaluator {
 }
 
 const NO_SUBSTITUTIONS: ParameterSubstitutions = new Map();
-const zeroes = [new IntConstant(BigInt(0)), new FloatConstant(0.0), new FloatConstant(-0.0)];
+const zeroes = [new IntConstant(0n), new FloatConstant(0.0), new FloatConstant(-0.0)];

src/language/validation/other/expressions/infixOperations.ts

@@ -10,7 +10,7 @@ export const divisionDivisorMustNotBeZero = (services: SafeDsServices) => {
     const partialEvaluator = services.evaluation.PartialEvaluator;
     const typeComputer = services.types.TypeComputer;
 
-    const zeroInt = new IntConstant(BigInt(0));
+    const zeroInt = new IntConstant(0n);
     const zeroFloat = new FloatConstant(0.0);
     const minusZeroFloat = new FloatConstant(-0.0);
 

syntaxes/safe-ds.tmLanguage.json

@@ -92,7 +92,7 @@
     },
     "string-character-escape": {
       "name": "constant.character.escape.safe-ds",
-      "match": "\\\\(x[0-9A-Fa-f]{2}|u[0-9A-Fa-f]{4}|u\\{[0-9A-Fa-f]+\\}|[0-2][0-7]{0,2}|3[0-6][0-7]?|37[0-7]?|[4-7][0-7]?|.|$)"
+      "match": "\\\\(b|f|n|r|t|v|0|'|\"|{|\\\\|u[0-9a-fA-F]{4})"
     }
   }
 }