refactore: start extracting visitors

Author: AndyOGo

src/visitors/allVisitor.js

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+import truthy from "../helpers/truthy";
+
+function allVisitor(data, values) {
+  const scopedData = apply(values[0], data);
+  const scopedLogic = values[1];
+  // All of an empty set is false. Note, some and none have correct fallback after the for loop
+  if( ! scopedData.length) {
+    return false;
+  }
+  for(let i=0; i < scopedData.length; i+=1) {
+    if( ! truthy( apply(scopedLogic, scopedData[i]) )) {
+      return false; // First falsy, short circuit
+    }
+  }
+  return true; // All were truthy
+}
+
+export default allVisitor;

src/visitors/andVisitor.js

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+import truthy from "../helpers/truthy";
+
+function andVisitor(data, values, current) {
+  for(let i=0; i < values.length; i++) {
+    current = apply(values[i], data);
+    if( ! truthy(current)) {
+      return current;
+    }
+  }
+  return current; // Last
+}
+
+export default andVisitor;

src/visitors/filterVisitor.js

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+import truthy from "../helpers/truthy";
+
+function filterVisitor(data, values) {
+  const scopedData = apply(values[0], data);
+  const scopedLogic = values[1];
+
+  if ( ! Array.isArray(scopedData)) {
+    return [];
+  }
+  // Return only the elements from the array in the first argument,
+  // that return truthy when passed to the logic in the second argument.
+  // For parity with JavaScript, reindex the returned array
+  return scopedData.filter(function(datum){
+    return truthy( apply(scopedLogic, datum));
+  });
+}
+
+export default filterVisitor

src/visitors/ifVisitor.js

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+import truthy from '../helpers/truthy';
+
+function ifVisitor(data, values) {
+  /* 'if' should be called with a odd number of parameters, 3 or greater
+    This works on the pattern:
+    if( 0 ){ 1 }else{ 2 };
+    if( 0 ){ 1 }else if( 2 ){ 3 }else{ 4 };
+    if( 0 ){ 1 }else if( 2 ){ 3 }else if( 4 ){ 5 }else{ 6 };
+
+    The implementation is:
+    For pairs of values (0,1 then 2,3 then 4,5 etc)
+    If the first evaluates truthy, evaluate and return the second
+    If the first evaluates falsy, jump to the next pair (e.g, 0,1 to 2,3)
+    given one parameter, evaluate and return it. (it's an Else and all the If/ElseIf were false)
+    given 0 parameters, return NULL (not great practice, but there was no Else)
+    */
+  for(let i = 0; i < values.length - 1; i += 2) {
+    if( truthy( apply(values[i], data) ) ) {
+      return apply(values[i+1], data);
+    }
+  }
+
+  if(values.length === i+1) {
+    return apply(values[i], data);
+  }
+
+  return null;
+};
+
+export default ifVisitor;

src/visitors/mapVisitor.js

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+function mapVisitor(data, values) {
+  const scopedData = apply(values[0], data);
+  const scopedLogic = values[1];
+
+  if ( ! Array.isArray(scopedData)) {
+    return [];
+  }
+
+  return scopedData.map(function(datum){
+    return apply(scopedLogic, datum);
+  });
+}
+
+export default mapVisitor;

src/visitors/noneVisitor.js

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+function noneVisitor(data, values) {
+  const filtered = apply({'filter' : values}, data);
+
+  return filtered.length === 0;
+}
+
+export default noneVisitor;

src/visitors/orVisitor.js

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+import truthy from "../helpers/truthy";
+
+function orVisitor(data, values, current) {
+  for(let i=0; i < values.length; i++) {
+    current = apply(values[i], data);
+    if( truthy(current) ) {
+      return current;
+    }
+  }
+  return current; // Last
+}
+
+export default orVisitor;

src/visitors/reduceVisitor.js

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+function reduceVisitor(data, values) {
+  const scopedData = apply(values[0], data);
+  const scopedLogic = values[1];
+  const initial = typeof values[2] !== 'undefined' ? values[2] : null;
+
+  if ( ! Array.isArray(scopedData)) {
+    return initial;
+  }
+
+  return scopedData.reduce(
+    function(accumulator, current){
+      return apply(
+        scopedLogic,
+        {'current':current, 'accumulator':accumulator}
+      );
+    },
+    initial
+  );
+}
+
+export default reduceVisitor;

src/visitors/someVisitor.js

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+function someVisitor(data, values) {
+  const filtered = apply({'filter' : values}, data);
+
+  return filtered.length > 0;
+}
+
+export default someVisitor;