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splitAtDelimiters.js (2959B)

      1 /* eslint no-constant-condition:0 */
      2 const findEndOfMath = function(delimiter, text, startIndex) {
      3     // Adapted from
      4     // https://github.com/Khan/perseus/blob/master/src/perseus-markdown.jsx
      5     let index = startIndex;
      6     let braceLevel = 0;
      7 
      8     const delimLength = delimiter.length;
      9 
     10     while (index < text.length) {
     11         const character = text[index];
     12 
     13         if (braceLevel <= 0 &&
     14             text.slice(index, index + delimLength) === delimiter) {
     15             return index;
     16         } else if (character === "\\") {
     17             index++;
     18         } else if (character === "{") {
     19             braceLevel++;
     20         } else if (character === "}") {
     21             braceLevel--;
     22         }
     23 
     24         index++;
     25     }
     26 
     27     return -1;
     28 };
     29 
     30 const splitAtDelimiters = function(startData, leftDelim, rightDelim, display) {
     31     const finalData = [];
     32 
     33     for (let i = 0; i < startData.length; i++) {
     34         if (startData[i].type === "text") {
     35             const text = startData[i].data;
     36 
     37             let lookingForLeft = true;
     38             let currIndex = 0;
     39             let nextIndex;
     40 
     41             nextIndex = text.indexOf(leftDelim);
     42             if (nextIndex !== -1) {
     43                 currIndex = nextIndex;
     44                 finalData.push({
     45                     type: "text",
     46                     data: text.slice(0, currIndex),
     47                 });
     48                 lookingForLeft = false;
     49             }
     50 
     51             while (true) {
     52                 if (lookingForLeft) {
     53                     nextIndex = text.indexOf(leftDelim, currIndex);
     54                     if (nextIndex === -1) {
     55                         break;
     56                     }
     57 
     58                     finalData.push({
     59                         type: "text",
     60                         data: text.slice(currIndex, nextIndex),
     61                     });
     62 
     63                     currIndex = nextIndex;
     64                 } else {
     65                     nextIndex = findEndOfMath(
     66                         rightDelim,
     67                         text,
     68                         currIndex + leftDelim.length);
     69                     if (nextIndex === -1) {
     70                         break;
     71                     }
     72 
     73                     finalData.push({
     74                         type: "math",
     75                         data: text.slice(
     76                             currIndex + leftDelim.length,
     77                             nextIndex),
     78                         rawData: text.slice(
     79                             currIndex,
     80                             nextIndex + rightDelim.length),
     81                         display: display,
     82                     });
     83 
     84                     currIndex = nextIndex + rightDelim.length;
     85                 }
     86 
     87                 lookingForLeft = !lookingForLeft;
     88             }
     89 
     90             finalData.push({
     91                 type: "text",
     92                 data: text.slice(currIndex),
     93             });
     94         } else {
     95             finalData.push(startData[i]);
     96         }
     97     }
     98 
     99     return finalData;
    100 };
    101 
    102 module.exports = splitAtDelimiters;