From 841fcb28076ae28efff7132cd35f37feef3582c8 Mon Sep 17 00:00:00 2001
From: cryptogopher <git6453hub@michalczyk.pro>
Date: Sun, 10 Nov 2019 00:48:54 +0100
Subject: [PATCH] Working on formula validation to accomodate functions, WIP

---
 config/locales/en.yml        |  6 ++--
 lib/body_tracking/formula.rb | 53 +++++++++++++++++++++++-------------
 2 files changed, 37 insertions(+), 22 deletions(-)

diff --git a/config/locales/en.yml b/config/locales/en.yml
index fabac86..73bc16a 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -26,11 +26,11 @@ en:
             parent:
               parent_domain_mismatch: 'parent quantity has to be in the same domain'
             formula:
-              invalid_formula: 'interpretation failed after: %{part}'
+              invalid_formula: 'interpretation failed: %{msg}'
               disallowed_token: 'includes disallowed token "%{token}"
                 (of type %{ttype}) at %{location}'
-              disallowed_function_call: 'includes disallowed function call %{function}'
-              unknown_quantity: 'contains undefined quantities: %{quantities}'
+              disallowed_function_call: 'includes disallowed function call: %{function}'
+              unknown_quantity: 'contains undefined quantity: %{quantity}'
   body_trackers:
     index:
       heading: 'Summary'
diff --git a/lib/body_tracking/formula.rb b/lib/body_tracking/formula.rb
index fdace66..275c317 100644
--- a/lib/body_tracking/formula.rb
+++ b/lib/body_tracking/formula.rb
@@ -2,6 +2,7 @@ module BodyTracking
   module Formula
     require 'ripper'
     QUANTITY_TTYPES = [:on_ident, :on_tstring_content, :on_const]
+    FUNCTIONS = ['abs', 'nil?']
 
     class Formula
       def initialize(project, formula)
@@ -13,19 +14,35 @@ module BodyTracking
         errors = []
 
         # 1st: check if formula is valid Ruby code
-        tokenized_length = Ripper.tokenize(@formula).join.length
-        unless tokenized_length == @formula.length
-          errors << [:invalid_formula, {part: @formula[0...tokenized_length]}]
+        #tokenized_length = Ripper.tokenize(@formula).join.length
+        #unless tokenized_length == @formula.length
+        #  errors << [:invalid_formula, {part: @formula[0...tokenized_length]}]
+        #end
+        begin
+          eval("-> { #{@formula} }")
+        rescue ScriptError => e
+          errors << [:invalid_formula, {msg: e.message}]
         end
 
         # 2nd: check if formula contains only allowed token types
+        # 3rd: check for disallowed function calls (they are not detected by Ripper.lex)
+        # FIXME: this is unreliable (?) detection of function calls, should be replaced
+        # with parsing Ripper.sexp if necessary
         identifiers = []
+        disallowed_functions = Set.new
+        prev_ttype, prev_token = nil, nil
         Ripper.lex(@formula).each do |location, ttype, token|
+          puts ttype, token
           case
-          when QUANTITY_TTYPES.include?(ttype)
+          when QUANTITY_TTYPES.include?(prev_ttype) && ttype == :on_lparen
+            disallowed_functions << prev_token unless FUNCTIONS.include?(prev_token)
+            identifiers -= [prev_token]
+          when prev_ttype == :on_period && QUANTITY_TTYPES.include?(ttype)
+            disallowed_functions << token unless FUNCTIONS.include?(token)
+          when is_token_quantity?(ttype, token)
             identifiers << token
           when [:on_sp, :on_int, :on_rational, :on_float, :on_tstring_beg, :on_tstring_end,
-                :on_lparen, :on_rparen].include?(ttype)
+                :on_lparen, :on_rparen, :on_period].include?(ttype)
           when :on_op == ttype &&
             ['+', '-', '*', '/', '%', '**', '==', '!=', '>', '<', '>=', '<=', '<=>', '===',
              '..', '...', '?:', 'and', 'or', 'not', '&&', '||', '!'].include?(token)
@@ -33,20 +50,14 @@ module BodyTracking
           else
             errors << [:disallowed_token, {token: token, ttype: ttype, location: location}]
           end
+          prev_ttype, prev_token = ttype, token unless ttype == :on_sp
         end
-
-        # 3rd: check for disallowed function calls (they are not detected by Ripper.lex)
-        # FIXME: this is unreliable (?) detection of function calls, should be replaced
-        # with parsing Ripper.sexp if necessary
-        function = Ripper.slice(@formula, 'ident [sp]* lparen')
-        errors << [:disallowed_function_call, {function: function}] if function
+        disallowed_functions.each { |f| errors << [:disallowed_function_call, {function: f}] }
 
         # 4th: check if identifiers used in formula correspond to existing quantities
         identifiers.uniq!
         quantities = @project.quantities.where(name: identifiers).pluck(:name)
-        if quantities.length != identifiers.length
-          errors << [:unknown_quantity, {quantities: identifiers - quantities}]
-        end
+        (identifiers - quantities).each { |q| errors << [:unknown_quantity, {quantity: q}] }
 
         errors
       end
@@ -57,27 +68,31 @@ module BodyTracking
 
       def get_quantities
         q_names = Ripper.lex(@formula).map do |*, ttype, token|
-          token if QUANTITY_TTYPES.include?(ttype)
+          token if is_token_quantity?(ttype, token)
         end.compact
         @project.quantities.where(name: q_names).to_a
       end
 
       def calculate(inputs)
         paramed_formula = Ripper.lex(@formula).map do |*, ttype, token|
-          QUANTITY_TTYPES.include?(ttype) ? "params['#{token}'].to_d" : token
+          is_token_quantity?(ttype, token) ? "params['#{token}'].to_d" : token
         end.join
 
         inputs.map do |i, values|
           begin
-            [i, get_binding(values).eval(paramed_formula)]
-          rescue
-            [i, nil]
+            [i, [get_binding(values).eval(paramed_formula), nil]]
+          rescue Exception
+            [i, [nil, nil]]
           end
         end
       end
 
       private
 
+      def is_token_quantity?(ttype, token)
+        QUANTITY_TTYPES.include?(ttype) && !FUNCTIONS.include?(token)
+      end
+
       def get_binding(params)
         binding
       end