88 lines
1.9 KiB
JavaScript
88 lines
1.9 KiB
JavaScript
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// string literal characters cannot contain control codes
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var CONTROL_CODES = [0, // null
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7, // bell
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8, // backspace
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9, // horizontal
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10, // line feed
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11, // vertical tab
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12, // form feed
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13, // carriage return
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26, // Control-Z
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27, // escape
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127 // delete
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]; // escaped sequences can either be a two character hex value, or one of the
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// following single character codes
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function decodeControlCharacter(char) {
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switch (char) {
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case "t":
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return 0x09;
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case "n":
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return 0x0a;
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case "r":
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return 0x0d;
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case '"':
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return 0x22;
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case "′":
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return 0x27;
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case "\\":
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return 0x5c;
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}
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return -1;
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}
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var ESCAPE_CHAR = 92; // backslash
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var QUOTE_CHAR = 34; // backslash
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// parse string as per the spec:
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// https://webassembly.github.io/spec/core/multipage/text/values.html#text-string
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export function parseString(value) {
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var byteArray = [];
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var index = 0;
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while (index < value.length) {
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var charCode = value.charCodeAt(index);
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if (CONTROL_CODES.indexOf(charCode) !== -1) {
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throw new Error("ASCII control characters are not permitted within string literals");
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}
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if (charCode === QUOTE_CHAR) {
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throw new Error("quotes are not permitted within string literals");
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}
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if (charCode === ESCAPE_CHAR) {
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var firstChar = value.substr(index + 1, 1);
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var decodedControlChar = decodeControlCharacter(firstChar);
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if (decodedControlChar !== -1) {
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// single character escaped values, e.g. \r
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byteArray.push(decodedControlChar);
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index += 2;
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} else {
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// hex escaped values, e.g. \2a
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var hexValue = value.substr(index + 1, 2);
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if (!/^[0-9A-F]{2}$/i.test(hexValue)) {
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throw new Error("invalid character encoding");
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}
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byteArray.push(parseInt(hexValue, 16));
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index += 3;
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}
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} else {
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// ASCII encoded values
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byteArray.push(charCode);
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index++;
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}
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}
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return byteArray;
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}
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