Merge pull request #8463 from voegelas/challenge-227

Evaluate strings

2 files changed, 43 insertions, 2 deletions

diff --git a/challenge-227/andreas-voegele/kotlin/ch-2.kts b/challenge-227/andreas-voegele/kotlin/ch-2.kts
index fd9d4f3e7a..7fe5e15c9a 100755
--- a/challenge-227/andreas-voegele/kotlin/ch-2.kts
+++ b/challenge-227/andreas-voegele/kotlin/ch-2.kts
@@ -108,11 +108,35 @@ class Roman private constructor(val number: Double) {
     override fun toString() = encodeRoman(number)
 }
 
+fun romanMaths(expression: String): Roman {
+    val functionFor = mapOf(
+        "+" to Roman::plus,
+        "-" to Roman::minus,
+        "*" to Roman::times,
+        "/" to Roman::div,
+        "%" to Roman::rem,
+        "**" to Roman::pow,
+    )
+    val match = Regex(
+        """
+        ([IVXLCDM]+)     # Numeral
+        \s*
+        ([-+*/%]|[*][*]) # Operator
+        \s*
+        ([IVXLCDM]+)     # Numeral
+        """,
+        RegexOption.COMMENTS,
+    ).matchEntire(expression)
+        ?: throw IllegalArgumentException("Invalid expression $expression")
+    val (x, op, y) = match.destructured
+    return functionFor[op]!!.invoke(Roman(x), Roman(y))
+}
+
 println(Roman("IV") + Roman("V"))
 println(Roman("M") - Roman("I"))
 println(Roman("X") / Roman("II"))
 println(Roman("XI") * Roman("VI"))
-println(Roman("VII").pow(Roman("III")))
+println(romanMaths("VII ** III"))
 println(Roman("V") - Roman("V"))
 println(Roman("V") / Roman("II"))
 println(Roman("MMM") + Roman("M"))
diff --git a/challenge-227/andreas-voegele/perl/ch-2.pl b/challenge-227/andreas-voegele/perl/ch-2.pl
index 0c253aa7cb..3ce453acda 100755
--- a/challenge-227/andreas-voegele/perl/ch-2.pl
+++ b/challenge-227/andreas-voegele/perl/ch-2.pl
@@ -110,15 +110,32 @@ use overload
 
 package main;
 
+use Carp qw(croak);
+
 sub roman ($string) {
     return Roman->new($string);
 }
 
+sub roman_maths ($expression) {
+    my ($x, $op, $y) = $expression =~ m{
+        \A
+        ([IVXLCDM]+)     # Numeral
+        \s*
+        ([-+*/%]|[*][*]) # Operator
+        \s*
+        ([IVXLCDM]+)     # Numeral
+        \z
+    }xms
+        or croak "Invalid expression $expression";
+    ## no critic (ProhibitStringyEval)
+    return eval qq{roman('$x') $op roman('$y')};
+}
+
 say roman('IV') + roman('V');
 say roman('M') - roman('I');
 say roman('X') / roman('II');
 say roman('XI') * roman('VI');
-say roman('VII')**roman('III');
+say roman_maths('VII ** III');
 say roman('V') - roman('V');
 say roman('V') / roman('II');
 say roman('MMM') + roman('M');