# All files / src/generator ternary-expression.js

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     // @flow
    import mapSyntax from "./map-syntax";
    import { generateValueType } from "./utils";
    import mergeBlock from "./merge-block";
    import opcode, { opcodeFromOperator } from "../emitter/opcode";
    import type { GeneratorType } from "./flow/types";

    const generateTernary: GeneratorType = (node, parent) => {
      // TernaryExpression has a simple param layout of 2(TWO) total parameters.
      // It's a single param for the boolean check followed by
      // another param which is a Pair Node containing the 2(TWO) param results of
      // true and false branches.
      // The whole thing is encoded as an implicitly retunred if/then/else block.
      const mapper = mapSyntax(parent);
      const resultPair = node.params[1];

      // Truthy check
      const block = node.params
        .slice(0, 1)
        .map(mapper)
        .reduce(mergeBlock, []);

      // If Opcode
      block.push({
        kind: opcodeFromOperator(node),
        valueType: generateValueType(node),
        params: [],
      });

      // Map the true branch
      block.push.apply(
        block,
        resultPair.params
          .slice(0, 1)
          .map(mapper)
          .reduce(mergeBlock, [])
      );
      block.push({
        kind: opcodeFromOperator({ value: ":", type: "i32" }),
        params: [],
      });

      // Map the false branch
      block.push.apply(
        block,
        resultPair.params
          .slice(-1)
          .map(mapper)
          .reduce(mergeBlock, [])
      );

      // Wrap up the node
      block.push({ kind: opcode.End, params: [] });

      return block;
    };

    export default generateTernary;