From 152e60f464fbedcd288b395e3fdd3bc4b13be618 Mon Sep 17 00:00:00 2001
From: Nico Rehwaldt <git_nikku@nixis.de>
Date: Wed, 1 Nov 2023 21:23:57 +0100
Subject: [PATCH] feat: stricly assert argument length

Closes https://github.com/nikku/feelin/issues/12


BREAKING CHANGE:

* functions with variable length arguments must use `...` to capture
  variable parts
---
 src/builtins.ts          | 28 ++++++++++++++--------------
 src/types.ts             | 33 +++++++++++++++++++++++++++++++--
 test/interpreter-spec.js | 39 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 84 insertions(+), 16 deletions(-)

diff --git a/src/builtins.ts b/src/builtins.ts
index 3ac5106..8e62b1a 100644
--- a/src/builtins.ts
+++ b/src/builtins.ts
@@ -375,25 +375,25 @@ const builtins = {
     return list.length;
   }, [ 'list' ]),
 
-  'min': listFn(function(list) {
+  'min': listFn(function(...list) {
     return list.reduce((min, el) => min === null ? el : Math.min(min, el), null);
   }, 'number'),
 
-  'max': listFn(function(list) {
+  'max': listFn(function(...list) {
     return list.reduce((max, el) => max === null ? el : Math.max(max, el), null);
   }, 'number'),
 
-  'sum': listFn(function(list) {
+  'sum': listFn(function(...list) {
     return sum(list);
   }, 'number'),
 
-  'mean': listFn(function(list) {
+  'mean': listFn(function(...list) {
     const s = sum(list);
 
     return s === null ? s : s / list.length;
   }, 'number'),
 
-  'all': listFn(function(list) {
+  'all': listFn(function(...list) {
 
     let nonBool = false;
 
@@ -412,7 +412,7 @@ const builtins = {
 
   }, 'any?'),
 
-  'any': listFn(function(list) {
+  'any': listFn(function(...list) {
 
     let nonBool = false;
 
@@ -478,7 +478,7 @@ const builtins = {
     }, []);
   }, [ 'list', 'any' ]),
 
-  'union': listFn(function(lists) {
+  'union': listFn(function(...lists) {
 
     return lists.reduce((result, list) => {
 
@@ -507,7 +507,7 @@ const builtins = {
     return flatten(list);
   }, [ 'list' ]),
 
-  'product': listFn(function(list) {
+  'product': listFn(function(...list) {
 
     if (list.length === 0) {
       return null;
@@ -518,7 +518,7 @@ const builtins = {
     }, 1);
   }, 'number'),
 
-  'median': listFn(function(list) {
+  'median': listFn(function(...list) {
 
     if (list.length === 0) {
       return null;
@@ -527,7 +527,7 @@ const builtins = {
     return median(list);
   }, 'number'),
 
-  'stddev': listFn(function(list) {
+  'stddev': listFn(function(...list) {
 
     if (list.length < 2) {
       return null;
@@ -536,7 +536,7 @@ const builtins = {
     return stddev(list);
   }, 'number'),
 
-  'mode': listFn(function(list) {
+  'mode': listFn(function(...list) {
     return mode(list);
   }, 'number'),
 
@@ -730,11 +730,11 @@ const builtins = {
     return Object.entries(m).map(([ key, value ]) => ({ key, value }));
   }, [ 'context' ]),
 
-  'context': listFn(function(_contexts) {
+  'context': listFn(function(..._contexts) {
     throw notImplemented('context');
   }, 'context'),
 
-  'context merge': listFn(function(_contexts) {
+  'context merge': listFn(function(..._contexts) {
     throw notImplemented('context merge');
   }, 'context'),
 
@@ -856,7 +856,7 @@ function listFn(fnDefinition, type, parameterNames = null) {
       return null;
     }
 
-    return fnDefinition(args);
+    return fnDefinition(...args);
   };
 
   wrappedFn.$args = parameterNames || parseParameterNames(fnDefinition);
diff --git a/src/types.ts b/src/types.ts
index 711d064..d63a05c 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -261,15 +261,44 @@ export class FunctionWrapper {
 
     if (isArray(contextOrArgs)) {
       params = contextOrArgs;
+
+      // reject
+      if (params.length > this.parameterNames.length) {
+
+        const lastParam = this.parameterNames[this.parameterNames.length - 1];
+
+        // strictly check for parameter count provided
+        // for non var-args functions
+        if (!lastParam || !lastParam.startsWith('...')) {
+          return null;
+        }
+      }
     } else {
 
       // strictly check for required parameter names,
       // and fail on wrong parameter name
-      if (Object.keys(contextOrArgs).some(key => !this.parameterNames.includes(key))) {
+      if (Object.keys(contextOrArgs).some(
+        key => !this.parameterNames.includes(key) && !this.parameterNames.includes(`...${key}`)
+      )) {
         return null;
       }
 
-      params = this.parameterNames.map(n => contextOrArgs[n]);
+      params = this.parameterNames.reduce((params, name) => {
+
+        if (name.startsWith('...')) {
+          name = name.slice(3);
+
+          const value = contextOrArgs[name];
+
+          if (!value) {
+            return params;
+          } else {
+            return [ ...params, ...value ];
+          }
+        }
+
+        return [ ...params, contextOrArgs[name] ];
+      }, []);
     }
 
     return this.fn.call(null, ...params);
diff --git a/test/interpreter-spec.js b/test/interpreter-spec.js
index 2e6fe3f..a903ae7 100644
--- a/test/interpreter-spec.js
+++ b/test/interpreter-spec.js
@@ -169,6 +169,45 @@ describe('interpreter', function() {
         b: 7
       });
 
+      // call with wrong args
+      expr('foo(5)', null, {
+        foo: function() {
+          return 5;
+        }
+      });
+
+      // var args function
+      expr('foo(1, 2, 3)', [ [ 1, 2, 3 ] ], {
+        foo: function(...varArgs) {
+          return [ varArgs ];
+        }
+      });
+
+      expr('foo(1)', [ 1, [] ], {
+        foo: function(firstArg, ...varArgs) {
+          return [ firstArg, varArgs ];
+        }
+      });
+
+      expr('foo(firstArg: 1)', [ 1, [] ], {
+        foo: function(firstArg, ...varArgs) {
+          return [ firstArg, varArgs ];
+        }
+      });
+
+      expr('foo(firstArg: 1, varArgs: null)', [ 1, [] ], {
+        foo: function(firstArg, ...varArgs) {
+          return [ firstArg, varArgs ];
+        }
+      });
+
+
+      expr('foo(varArgs: [ 1, 2, 3 ])', [ [ 1, 2, 3 ] ], {
+        foo: function(...varArgs) {
+          return [ varArgs ];
+        }
+      });
+
     });