simple-squiggle

A restricted subset of Squiggle
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first_in_statement.js (1974B)

      1 import {
      2     AST_Binary,
      3     AST_Conditional,
      4     AST_Dot,
      5     AST_Object,
      6     AST_Sequence,
      7     AST_Statement,
      8     AST_Sub,
      9     AST_UnaryPostfix,
     10     AST_PrefixedTemplateString
     11 } from "../ast.js";
     12 
     13 // return true if the node at the top of the stack (that means the
     14 // innermost node in the current output) is lexically the first in
     15 // a statement.
     16 function first_in_statement(stack) {
     17     let node = stack.parent(-1);
     18     for (let i = 0, p; p = stack.parent(i); i++) {
     19         if (p instanceof AST_Statement && p.body === node)
     20             return true;
     21         if ((p instanceof AST_Sequence && p.expressions[0] === node) ||
     22             (p.TYPE === "Call" && p.expression === node) ||
     23             (p instanceof AST_PrefixedTemplateString && p.prefix === node) ||
     24             (p instanceof AST_Dot && p.expression === node) ||
     25             (p instanceof AST_Sub && p.expression === node) ||
     26             (p instanceof AST_Conditional && p.condition === node) ||
     27             (p instanceof AST_Binary && p.left === node) ||
     28             (p instanceof AST_UnaryPostfix && p.expression === node)
     29         ) {
     30             node = p;
     31         } else {
     32             return false;
     33         }
     34     }
     35 }
     36 
     37 // Returns whether the leftmost item in the expression is an object
     38 function left_is_object(node) {
     39     if (node instanceof AST_Object) return true;
     40     if (node instanceof AST_Sequence) return left_is_object(node.expressions[0]);
     41     if (node.TYPE === "Call") return left_is_object(node.expression);
     42     if (node instanceof AST_PrefixedTemplateString) return left_is_object(node.prefix);
     43     if (node instanceof AST_Dot || node instanceof AST_Sub) return left_is_object(node.expression);
     44     if (node instanceof AST_Conditional) return left_is_object(node.condition);
     45     if (node instanceof AST_Binary) return left_is_object(node.left);
     46     if (node instanceof AST_UnaryPostfix) return left_is_object(node.expression);
     47     return false;
     48 }
     49 
     50 export { first_in_statement, left_is_object };