add error messages for rule syntax

src/reducers/reducer.init.js

@@ -15,8 +15,8 @@ export const initState = (changesArgument: number): stateType => {
           'a>ɯ/._#',
           '[+ sonorant - low rounded high back]>0/._.',
           '[+ obstruent]>[+ obstruent aspirated ]/#_.',
-          '[+ sonorant - rounded]>[+ sonorant + rounded]/._#'
-          // 'nn>nun/._.',
+          '[+ sonorant - rounded]>[+ sonorant + rounded]/._#',
+          'nn>nun/._.'
         ]
       }
     ],

src/reducers/reducer.results.js

@@ -64,13 +64,29 @@ const findFeaturesFromGrapheme = (phones: {}, lexeme:string): [] => {
   return featureBundle;
 }
 
-const decomposeRule = (rule: string): ruleBundle => {
+const errorMessage = ([prefix, separator], location, err) => `${prefix}${location}${separator}${err}`
+
+const lintRule = (rule) => {
+  if (rule.match(/>/g) === null) throw `Insert '>' operator between target and result`
+  if (rule.match(/\//g) === null) throw `Insert '/' operator between change and environment`
+  if (rule.match(/_/g) === null) throw `Insert '_' operator in environment`
+  if (rule.match(/>/g).length > 1) throw `Too many '>' operators`
+  if (rule.match(/\//g).length > 1) throw `Too many '/' operators`
+  if (rule.match(/_/g).length > 1) throw `Too many '_' operators`
+  return rule.split(/>|\/|_/g);
+}
+
+const decomposeRule = (rule: string, index: number): ruleBundle => {
   // splits rule at '>' '/' and '_' substrings resulting in array of length 4
-  const [position, newFeatures, pre, post] = rule.split(/>|\/|_/g); 
+  try {
+    const [position, newFeatures, pre, post] = lintRule(rule); 
     return {
       environment: { pre, position, post },
       newFeatures
     }
+  } catch (err) {
+    throw errorMessage`Error in line ${index + 1}: ${err}`;
+  }
 }
 
 const getPositiveFeatures = phoneme => {
@@ -125,7 +141,13 @@ const mapRuleBundleToFeatureBundle =  phones => ruleBundle => {
 
 export const decomposeRules = (epoch: epochType, phones: {[key: string]: phoneType}): decomposedRulesType => {
   const { changes } = epoch
-  return changes.map(decomposeRule).map(mapRuleBundleToFeatureBundle(phones));
+  try {
+    return changes
+      .map(decomposeRule)
+      .map(mapRuleBundleToFeatureBundle(phones));
+  } catch (err) {
+    return err;
+  }
 }
 
 const isPhonemeBoundByRule  = phonemeFeatures => (ruleFeature, index) => {

src/reducers/reducer.results.test.js

@@ -14,77 +14,54 @@ describe('Results', () => {
   });
 
   it('rules decomposed properly', () => {
-    const epoch = initState().epochs[0];
-    epoch.changes = epoch.changes.slice(0,1)
-    const phones = initState().phones;
-    const result = [
-      {
-        // ! '[+ occlusive - nasal]>[+ occlusive nasal]/n_',
-        environment: {
-          pre: [
-            {
-              sonorant: true, nasal: true, occlusive: true, coronal: true
-            }
-          ],
-          position: [
-            {occlusive: true, nasal: false}
-          ],
-          post: [],
-        },
-        newFeatures: [{occlusive: true, nasal: true}]
-      }
-    ];
-    expect(decomposeRules(epoch, phones)).toStrictEqual(result);
+    const { epochs, phones } = initState(1);
+    const result = getResult();
+    expect(decomposeRules(epochs[0], phones)).toStrictEqual(result);
   });
 
-  it('expect transform lexeme to apply rule to lexeme', () => {
-    const lexemeBundle = [
-      {
-        grapheme: 'a',
-        features: {
-          sonorant: true,
-          back: true,
-          low: true,
-          high: false,
-          rounded: false
-        }
-      },
-      {
-        grapheme: 'n',
-        features: { sonorant: true, nasal: true, occlusive: true, coronal: true }
-      },
-      {
-        grapheme: 't',
-        features: { occlusive: true, coronal: true, obstruent: true, nasal: false }
-      },
-      {
-        grapheme: 'a',
-        features: {
-          sonorant: true,
-          back: true,
-          low: true,
-          high: false,
-          rounded: false
-        }
-      }
-    ]
-
-    const resultsLexeme = [...lexemeBundle]
-    resultsLexeme[2] = lexemeBundle[1]
-    
-    const rule = {
-      environment: { 
-        pre: [ { sonorant: true, nasal: true, occlusive: true, coronal: true } ],
-        position: [ { occlusive: true, nasal: false } ],
-        post: [] 
-      },
-      newFeatures: [ { occlusive: true, nasal: true } ]
-    }
-
-    expect(transformLexeme(lexemeBundle, rule, initState().features)).toEqual(resultsLexeme)
-
+  it('rule without ">" returns helpful error message', () => {
+    const { phones } = initState();
+    const epoch = { name: 'error epoch', changes: [ 't/n/_' ] }
+    expect(decomposeRules(epoch, phones)).toEqual("Error in line 1: Insert '>' operator between target and result");
   })
 
+  it('rule with too many ">" returns helpful error message', () => {
+    const { phones } = initState();
+    const epoch = { name: 'error epoch', changes: [ 't>n>/_' ] }
+    expect(decomposeRules(epoch, phones)).toEqual("Error in line 1: Too many '>' operators");
+  })
+
+  it('rule without "/" returns helpful error message', () => {
+    const { phones } = initState();
+    const epoch = { name: 'error epoch', changes: [ 't>n_' ] }
+    expect(decomposeRules(epoch, phones)).toEqual("Error in line 1: Insert '/' operator between change and environment");
+  })
+
+  it('rule with too many "/" returns helpful error message', () => {
+    const { phones } = initState();
+    const epoch = { name: 'error epoch', changes: [ 't>n/_/' ] }
+    expect(decomposeRules(epoch, phones)).toEqual("Error in line 1: Too many '/' operators");
+  })
+
+  it('rule without "_" returns helpful error message', () => {
+    const { phones } = initState();
+    const epoch = { name: 'error epoch', changes: [ 't>n/' ] }
+    expect(decomposeRules(epoch, phones)).toEqual("Error in line 1: Insert '_' operator in environment");
+  })
+
+  it('rule with too many "_" returns helpful error message', () => {
+    const { phones } = initState();
+    const epoch = { name: 'error epoch', changes: [ 't>n/__' ] }
+    expect(decomposeRules(epoch, phones)).toEqual("Error in line 1: Too many '_' operators");
+  })
+
+  it('expect transform lexeme to apply rule to lexeme', () => {
+    const lexemeBundle = getlexemeBundle();
+    const resultsLexeme = [...lexemeBundle]
+    resultsLexeme[2] = lexemeBundle[1]
+    const rule = getRule();
+    expect(transformLexeme(lexemeBundle, rule, initState().features)).toEqual(resultsLexeme)
+  })
 
   it('results returned from first sound change rule', () => {
     const action = {type: 'RUN'};
@@ -151,18 +128,76 @@ describe('Results', () => {
     ]);
   });
 
-  // if('results returned from sound change suite', () => {
+
+  // it('results returned through sixth sound change rule', () => {
   //   const action = {type: 'RUN'};
-  //   state = initState()
-  //   console.log(stateReducer(state, action).results)
+  //   state = initState(5)
   //   expect(stateReducer(state, action).results).toEqual([
   //     {
   //       pass: 'epoch 1',
   //       lexicon: [
-  //         'anna', 'anta', 'anət', 'anna', 'tan', 'ənna'
+  //         'anunu', 'anat', 'ant', 'anunu', 'tʰan', 'nunu'
   //       ]
   //     }
   //   ]);
   // });
 
 });
+
+
+const getlexemeBundle = () => ([
+  {
+    grapheme: 'a',
+    features: {
+      sonorant: true,
+      back: true,
+      low: true,
+      high: false,
+      rounded: false
+    }
+  },
+  {
+    grapheme: 'n',
+    features: { sonorant: true, nasal: true, occlusive: true, coronal: true }
+  },
+  {
+    grapheme: 't',
+    features: { occlusive: true, coronal: true, obstruent: true, nasal: false }
+  },
+  {
+    grapheme: 'a',
+    features: {
+      sonorant: true,
+      back: true,
+      low: true,
+      high: false,
+      rounded: false
+    }
+  }
+])
+
+const getRule = () => ({
+  environment: { 
+    pre: [ { sonorant: true, nasal: true, occlusive: true, coronal: true } ],
+    position: [ { occlusive: true, nasal: false } ],
+    post: [] 
+  },
+  newFeatures: [ { occlusive: true, nasal: true } ]
+})
+
+const getResult = () => ([
+  {
+    environment: {
+      pre: [
+        {
+          sonorant: true, nasal: true, occlusive: true, coronal: true
+        }
+      ],
+      position: [
+        {occlusive: true, nasal: false}
+      ],
+      post: [],
+    },
+    newFeatures: [{occlusive: true, nasal: true}]
+  }
+]);