From b12744d831c4158671fc22401590eaac00f7c141 Mon Sep 17 00:00:00 2001
From: Bruce Hill <bitbucket@bruce-hill.com>
Date: Thu, 14 Jun 2018 23:25:05 -0700
Subject: Some cleanup and fixes. Simplifying a lot of code, and extending the
 flexibility of scoping. Redesigned Object system too.

---
 core/errors.nom | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

(limited to 'core/errors.nom')

diff --git a/core/errors.nom b/core/errors.nom
index dc585be..8c6261a 100644
--- a/core/errors.nom
+++ b/core/errors.nom
@@ -20,3 +20,49 @@ compile [assume %condition or barf %message] to
         if not \(%condition as lua expr) then
             error(\(%message as lua expr), 0);
         end
+
+# Try/except
+immediately
+    compile [..]
+        try %action and if it succeeds %success or if it barfs %msg %fallback
+        try %action and if it barfs %msg %fallback or if it succeeds %success
+    ..to
+        Lua ".."
+            do
+                local fell_through = false
+                local err, erred = nil, false
+                local ok, ret = xpcall(function()
+                    \(%action as lua statements)
+                    fell_through = true
+                end, function(\(%msg as lua expr))
+                    local ok, ret = pcall(function()
+                        \(%fallback as lua statements)
+                    end)
+                    if not ok then err, erred = ret, true end
+                end)
+                if ok then
+                    \(%success as lua statements)
+                    if not fell_through then
+                        return ret
+                    end
+                elseif erred then
+                    error(err, 0)
+                end
+            end
+immediately
+    parse [..]
+        try %action and if it succeeds %success or if it barfs %fallback
+        try %action and if it barfs %fallback or if it succeeds %success
+    ..as: try %action and if it succeeds %success or if it barfs (=lua "") %fallback
+immediately
+    parse [try %action] as
+        try %action and if it succeeds: do nothing
+        ..or if it barfs: do nothing
+    parse [try %action and if it barfs %fallback] as
+        try %action and if it succeeds: do nothing
+        ..or if it barfs %fallback
+    parse [try %action and if it barfs %msg %fallback] as
+        try %action and if it succeeds: do nothing
+        ..or if it barfs %msg %fallback
+    parse [try %action and if it succeeds %success] as
+        try %action and if it succeeds %success or if it barfs: do nothing
-- 
cgit v1.2.3