Christopher Chedeau
cf45afba61
- This brings in the flow test suite that contains a ton of JavaScript parsing edge cases - This creates snapshot tests using the pretty printer for all of them - If uncomment `RUN_AST_TESTS` line in `tests/run_specs.js`, it checks ast(pretty_print(x)) == ast(x). Right now, "178 failed, 197 passed, 375 of 377 total". So half of the tests are not passing, most of them are crashes and many of the rest are subtle issues.
35 lines
1008 B
JavaScript
35 lines
1008 B
JavaScript
/**
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* @flow
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*/
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/**
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* @param {number} codeUnit A Unicode code-unit, in range [0, 0x10FFFF]
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* @return {boolean} Whether code-unit is in a surrogate (hi/low) range
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*/
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function inSurrogateRange(codeUnit) {
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return 0xD800 <= codeUnit && codeUnit <= 0xDFFF;
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}
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/**
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* Return the length of the original Unicode character at given position in the
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* String by looking into the UTF-16 code unit; that is equal to 1 for any
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* non-surrogate characters in BMP ([U+0000..U+D7FF] and [U+E000, U+FFFF]); and
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* returns 2 for the hi/low surrogates ([U+D800..U+DFFF]), which are in fact
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* representing non-BMP characters ([U+10000..U+10FFFF]).
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*
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* Examples:
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* - '\u0020' => 1
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* - '\u3020' => 1
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* - '\uD835' => 2
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* - '\uD835\uDDEF' => 2
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* - '\uDDEF' => 2
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*
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* @param {string} str Non-empty string
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* @param {number} pos Position in the string to look for one code unit
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* @return {number} Number 1 or 2
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*/
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function utf16Length(str, pos) {
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return 1 + inSurrogateRange(str.charCodeAt(pos));
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}
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