51 lines
1.9 KiB
JavaScript
51 lines
1.9 KiB
JavaScript
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import {
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AST_Binary,
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AST_Conditional,
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AST_Dot,
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AST_Object,
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AST_Sequence,
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AST_Statement,
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AST_Sub,
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AST_UnaryPostfix,
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AST_PrefixedTemplateString
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} from "../ast.js";
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// return true if the node at the top of the stack (that means the
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// innermost node in the current output) is lexically the first in
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// a statement.
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function first_in_statement(stack) {
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let node = stack.parent(-1);
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for (let i = 0, p; p = stack.parent(i); i++) {
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if (p instanceof AST_Statement && p.body === node)
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return true;
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if ((p instanceof AST_Sequence && p.expressions[0] === node) ||
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(p.TYPE === "Call" && p.expression === node) ||
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(p instanceof AST_PrefixedTemplateString && p.prefix === node) ||
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(p instanceof AST_Dot && p.expression === node) ||
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(p instanceof AST_Sub && p.expression === node) ||
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(p instanceof AST_Conditional && p.condition === node) ||
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(p instanceof AST_Binary && p.left === node) ||
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(p instanceof AST_UnaryPostfix && p.expression === node)
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) {
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node = p;
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} else {
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return false;
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}
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}
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}
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// Returns whether the leftmost item in the expression is an object
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function left_is_object(node) {
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if (node instanceof AST_Object) return true;
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if (node instanceof AST_Sequence) return left_is_object(node.expressions[0]);
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if (node.TYPE === "Call") return left_is_object(node.expression);
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if (node instanceof AST_PrefixedTemplateString) return left_is_object(node.prefix);
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if (node instanceof AST_Dot || node instanceof AST_Sub) return left_is_object(node.expression);
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if (node instanceof AST_Conditional) return left_is_object(node.condition);
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if (node instanceof AST_Binary) return left_is_object(node.left);
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if (node instanceof AST_UnaryPostfix) return left_is_object(node.expression);
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return false;
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}
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export { first_in_statement, left_is_object };
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