Support _ in String[toInt|toIntOrNull|toFloat|toFloatOrNull] (#580)

The logic is the same as the Pkl parser

pkl-core/src/main/java/org/pkl/core/stdlib/base/StringNodes.java

@@ -768,7 +768,7 @@ public final class StringNodes {
     @Specialization
     protected long eval(String self) {
       try {
-        return Long.parseLong(self.replaceAll("_", ""));
+        return Long.parseLong(removeUnderlinesFromNumber(self));
       } catch (NumberFormatException e) {
         throw exceptionBuilder()
             .evalError("cannotParseStringAs", "Int")
@@ -783,7 +783,7 @@ public final class StringNodes {
     @Specialization
     protected Object eval(String self) {
       try {
-        return Long.parseLong(self.replaceAll("_", ""));
+        return Long.parseLong(removeUnderlinesFromNumber(self));
       } catch (NumberFormatException e) {
         return VmNull.withoutDefault();
       }
@@ -795,7 +795,7 @@ public final class StringNodes {
     @Specialization
     protected double eval(String self) {
       try {
-        return Double.parseDouble(self);
+        return Double.parseDouble(removeUnderlinesFromNumber(self));
       } catch (NumberFormatException e) {
         throw exceptionBuilder()
             .evalError("cannotParseStringAs", "Float")
@@ -810,7 +810,7 @@ public final class StringNodes {
     @Specialization
     protected Object eval(String self) {
       try {
-        return Double.parseDouble(self);
+        return Double.parseDouble(removeUnderlinesFromNumber(self));
       } catch (NumberFormatException e) {
         return VmNull.withoutDefault();
       }
@@ -934,4 +934,23 @@ public final class StringNodes {
     var replacement = mapper.applyString(regexMatch);
     return Matcher.quoteReplacement(replacement);
   }
+
+  /**
+   * Removes `_` from numbers to be parsed to be compatible with how Pkl parses numbers. Will return
+   * the string unmodified if it's invalid.
+   */
+  private static String removeUnderlinesFromNumber(String number) {
+    var builder = new StringBuilder();
+    var numberStart = true;
+    for (var i = 0; i < number.length(); i++) {
+      var c = number.charAt(i);
+      if (c != '_') {
+        builder.append(c);
+      } else if (numberStart) return number;
+
+      numberStart = c == '.' || c == 'e' || c == 'E';
+    }
+
+    return builder.toString();
+  }
 }

pkl-core/src/test/files/LanguageSnippetTests/input/api/string.pkl

@@ -233,19 +233,21 @@ examples {
     module.catch(() -> "9223372036854775808".toInt())
     module.catch(() -> "-9223372036854775809".toInt())
     module.catch(() -> "abc".toInt())
+    module.catch(() -> "_1_000".toInt())
   }
 
   ["toIntOrNull()"] {
     "123".toIntOrNull()
     "-123".toIntOrNull()
-    "1_2__3___".toInt()
+    "1_2__3___".toIntOrNull()
-    "-1_2__3___".toInt()
+    "-1_2__3___".toIntOrNull()
     "0".toIntOrNull()
     "-0".toIntOrNull()
     "1.2".toIntOrNull()
     "9223372036854775808".toIntOrNull()
     "-9223372036854775809".toIntOrNull()
     "abc".toIntOrNull()
+    "_1_2__3___".toIntOrNull()
   }
 
   ["toFloat()"] {
@@ -282,13 +284,17 @@ examples {
     "-.45e-9".toFloat()
     "9e1024".toFloat()
     "-9e1024".toFloat()
+    "-1_2__3___.2_e+1_".toFloat()
     module.catch(() -> "abc".toFloat())
+    module.catch(() -> "123._34".toFloat())
+    module.catch(() -> "123e_34".toFloat())
   }
 
   ["toFloatOrNull()"] {
     "0".toFloatOrNull()
     "-0".toFloatOrNull()
     "abc".toFloatOrNull()
+    "_123_.1_".toFloatOrNull()
   }
 
   ["take()"] {

pkl-core/src/test/files/LanguageSnippetTests/output/api/string.pcf

@@ -191,6 +191,7 @@ examples {
     "Cannot parse string as `Int`. String: \"9223372036854775808\""
     "Cannot parse string as `Int`. String: \"-9223372036854775809\""
     "Cannot parse string as `Int`. String: \"abc\""
+    "Cannot parse string as `Int`. String: \"_1_000\""
   }
   ["toIntOrNull()"] {
     123
@@ -203,6 +204,7 @@ examples {
     null
     null
     null
+    null
   }
   ["toFloat()"] {
     0.0
@@ -238,12 +240,16 @@ examples {
     -4.5E-10
     Infinity
     -Infinity
+    -1232.0
     "Cannot parse string as `Float`. String: \"abc\""
+    "Cannot parse string as `Float`. String: \"123._34\""
+    "Cannot parse string as `Float`. String: \"123e_34\""
   }
   ["toFloatOrNull()"] {
     0.0
     -0.0
     null
+    null
   }
   ["take()"] {
     ""