From 11e6cfeb82225253fb041565f5404564db881a4c Mon Sep 17 00:00:00 2001
From: ridiculousfish <corydoras@ridiculousfish.com>
Date: Sun, 17 Dec 2017 14:41:55 -0800
Subject: [PATCH] [math] Remove exception handling in builtin_math

This handles errors explicitly instead of catching them.
---
 src/builtin_math.cpp | 54 ++++++++++++++++++++++++--------------------
 1 file changed, 29 insertions(+), 25 deletions(-)

diff --git a/src/builtin_math.cpp b/src/builtin_math.cpp
index ba61af8fb..e86e6039a 100644
--- a/src/builtin_math.cpp
+++ b/src/builtin_math.cpp
@@ -119,36 +119,40 @@ static const wchar_t *math_get_arg(int *argidx, wchar_t **argv, wcstring *storag
 static mu::ValueOrError moduloOperator(double v, double w) { return (int)v % std::max(1, (int)w); };
 
 /// Evaluate math expressions.
-static int evaluate_expression(wchar_t *cmd, parser_t &parser, io_streams_t &streams,
+static int evaluate_expression(const wchar_t *cmd, parser_t &parser, io_streams_t &streams,
                                math_cmd_opts_t &opts, wcstring &expression) {
     UNUSED(parser);
 
-    try {
-        mu::Parser p;
-        // MuParser doesn't implement the modulo operator so we add it ourselves since there are
-        // likely users of our old math wrapper around bc that expect it to be available.
-        p.DefineOprtChars(L"%");
-        p.DefineOprt(L"%", moduloOperator, mu::prINFIX);
-
-        mu::OptionalError oerr = p.SetExpr(expression);
-        if (oerr.has_error()) throw oerr.error();
-        std::vector<mu::ValueOrError> vs;
-        p.Eval(&vs);
-        for (const mu::ValueOrError &v : vs) {
-            if (v.has_error()) throw v.error();
-        }
-        for (const mu::ValueOrError &v : vs) {
-            if (opts.scale == 0) {
-                streams.out.append_format(L"%ld\n", static_cast<long>(*v));
-            } else {
-                streams.out.append_format(L"%.*lf\n", opts.scale, *v);
-            }
-        }
-        return STATUS_CMD_OK;
-    } catch (mu::Parser::exception_type &e) {
-        streams.err.append_format(_(L"%ls: Invalid expression: %ls\n"), cmd, e.GetMsg().c_str());
+    // Helper to print an error and return an error code.
+    auto printError = [&streams, cmd](const mu::ParserError &err) {
+        streams.err.append_format(_(L"%ls: Invalid expression: %ls\n"), cmd, err.GetMsg().c_str());
         return STATUS_CMD_ERROR;
+    };
+
+    mu::Parser p;
+    // MuParser doesn't implement the modulo operator so we add it ourselves since there are
+    // likely users of our old math wrapper around bc that expect it to be available.
+    p.DefineOprtChars(L"%");
+    mu::OptionalError oerr = p.DefineOprt(L"%", moduloOperator, mu::prINFIX);
+    assert(!oerr.has_error() && "Unexpected error defining modulo operator");
+    (void)oerr;
+
+    oerr = p.SetExpr(expression);
+    if (oerr.has_error()) return printError(oerr.error());
+
+    std::vector<mu::ValueOrError> vs;
+    p.Eval(&vs);
+    for (const mu::ValueOrError &v : vs) {
+        if (v.has_error()) return printError(v.error());
     }
+    for (const mu::ValueOrError &v : vs) {
+        if (opts.scale == 0) {
+            streams.out.append_format(L"%ld\n", static_cast<long>(*v));
+        } else {
+            streams.out.append_format(L"%.*lf\n", opts.scale, *v);
+        }
+    }
+    return STATUS_CMD_OK;
 }
 
 /// The math builtin evaluates math expressions.