function jsonValue()

in packages/sqrl-jsonpath/src/index.ts [24:63]
32 lines of code
9 McCabe index (conditional complexity)

    function jsonValue(state: CompileState, ast): Ast {
      const pathAst = ast.args[1];
      if (pathAst.type !== "constant") {
        throw new Error("Expected constant");
      }
      const fullPath = pathAst.value;

      // @TODO: At some point in the future we should try handle the full
      // JSONPath spec. I'm hesitent to use libraries though since they'll be a
      // bit slower and implementations might change when we rewrite our core.
      let path = fullPath;
      let result = ast.args[0];
      while (path !== "$") {
        // See if we can find something to select, throw if not
        let select = null;
        if (path.startsWith("$.")) {
          const match = /^\$\.([$_a-zA-Z][$_a-zA-Z0-9]*)(.*?)$/.exec(path);
          if (match) {
            select = match[1];
            path = "$" + match[2];
          }
        } else if (path.startsWith("$[")) {
          const match = JSON_BRAKET_REGEX.exec(path);
          if (match) {
            select = match[1];
            path = "$" + match[2];

            // If we matched a quoted string, remove escaping
            if (select.startsWith("'") || select.startsWith('"')) {
              select = select.substring(1, select.length - 1);
              select = select.replace(/\\(.)/, "$1");
            }
          }
        }

        sqrlInvariant(ast, select, "JSONPath is not supported:: %s", fullPath);
        result = AstBuilder.call("attr", [result, AstBuilder.constant(select)]);
      }
      return result;
    },