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Merge pull request #18 from bartlomieju/decode_data_row
First pass at decoding data rows
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import { Oid } from "./oid.ts"; | ||
import { Column, Format } from "./connection.ts"; | ||
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// Datetime parsing based on: | ||
// https://github.com/bendrucker/postgres-date/blob/master/index.js | ||
const DATETIME_RE = /^(\d{1,})-(\d{2})-(\d{2}) (\d{2}):(\d{2}):(\d{2})(\.\d{1,})?/; | ||
const DATE_RE = /^(\d{1,})-(\d{2})-(\d{2})$/; | ||
const TIMEZONE_RE = /([Z+-])(\d{2})?:?(\d{2})?:?(\d{2})?/; | ||
const BC_RE = /BC$/; | ||
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function decodeDate(dateStr: string): null | Date { | ||
const matches = DATE_RE.exec(dateStr); | ||
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if (!matches) { | ||
return null; | ||
} | ||
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const year = parseInt(matches[1], 10); | ||
// remember JS dates are 0-based | ||
const month = parseInt(matches[2], 10) - 1; | ||
const day = parseInt(matches[3], 10); | ||
const date = new Date(year, month, day); | ||
// use `setUTCFullYear` because if date is from first | ||
// century `Date`'s compatibility for millenium bug | ||
// would set it as 19XX | ||
date.setUTCFullYear(year); | ||
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return date; | ||
} | ||
/** | ||
* Decode numerical timezone offset from provided date string. | ||
* | ||
* Matched these kinds: | ||
* - `Z (UTC)` | ||
* - `-05` | ||
* - `+06:30` | ||
* - `+06:30:10` | ||
* | ||
* Returns offset in miliseconds. | ||
*/ | ||
function decodeTimezoneOffset(dateStr: string): null | number { | ||
// get rid of date part as TIMEZONE_RE would match '-MM` part | ||
const timeStr = dateStr.split(' ')[1]; | ||
const matches = TIMEZONE_RE.exec(timeStr); | ||
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if (!matches) { | ||
return null; | ||
} | ||
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const type = matches[1]; | ||
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if (type === "Z") { | ||
// Zulu timezone === UTC === 0 | ||
return 0; | ||
} | ||
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// in JS timezone offsets are reversed, ie. timezones | ||
// that are "positive" (+01:00) are represented as negative | ||
// offsets and vice-versa | ||
const sign = type === '-' ? 1 : -1; | ||
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const hours = parseInt(matches[2], 10); | ||
const minutes = parseInt(matches[3] || "0", 10); | ||
const seconds = parseInt(matches[4] || "0", 10); | ||
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const offset = (hours * 3600) + (minutes * 60) + seconds; | ||
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return sign * offset * 1000; | ||
} | ||
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function decodeDatetime(dateStr: string): null | number | Date { | ||
/** | ||
* Postgres uses ISO 8601 style date output by default: | ||
* 1997-12-17 07:37:16-08 | ||
*/ | ||
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// there are special `infinity` and `-infinity` | ||
// cases representing out-of-range dates | ||
if (dateStr === 'infinity') { | ||
return Number(Infinity); | ||
} else if (dateStr === "-infinity") { | ||
return Number(-Infinity); | ||
} | ||
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const matches = DATETIME_RE.exec(dateStr); | ||
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if (!matches) { | ||
return decodeDate(dateStr); | ||
} | ||
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const isBC = BC_RE.test(dateStr); | ||
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const year = parseInt(matches[1], 10) * (isBC ? -1 : 1); | ||
// remember JS dates are 0-based | ||
const month = parseInt(matches[2], 10) - 1; | ||
const day = parseInt(matches[3], 10); | ||
const hour = parseInt(matches[4], 10); | ||
const minute = parseInt(matches[5], 10); | ||
const second = parseInt(matches[6], 10); | ||
// ms are written as .007 | ||
const msMatch = matches[7]; | ||
const ms = msMatch ? 1000 * parseFloat(msMatch) : 0; | ||
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let date: Date; | ||
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const offset = decodeTimezoneOffset(dateStr); | ||
if (offset === null) { | ||
date = new Date(year, month, day, hour, minute, second, ms); | ||
} else { | ||
// This returns miliseconds from 1 January, 1970, 00:00:00, | ||
// adding decoded timezone offset will construct proper date object. | ||
const utc = Date.UTC(year, month, day, hour, minute, second, ms); | ||
date = new Date(utc + offset); | ||
} | ||
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// use `setUTCFullYear` because if date is from first | ||
// century `Date`'s compatibility for millenium bug | ||
// would set it as 19XX | ||
date.setUTCFullYear(year); | ||
return date; | ||
} | ||
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function decodeBinary() { | ||
throw new Error("Not implemented!") | ||
} | ||
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const decoder = new TextDecoder(); | ||
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function decodeText(value: Uint8Array, typeOid: number): any { | ||
const strValue = decoder.decode(value); | ||
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switch (typeOid) { | ||
case Oid.char: | ||
case Oid.varchar: | ||
case Oid.text: | ||
case Oid.time: | ||
case Oid.timetz: | ||
return strValue; | ||
case Oid.bool: | ||
return strValue[0] === "t"; | ||
case Oid.int2: | ||
case Oid.int4: | ||
case Oid.int8: | ||
return parseInt(strValue, 10); | ||
case Oid.float4: | ||
case Oid.float8: | ||
return parseFloat(strValue); | ||
case Oid.timestamptz: | ||
case Oid.timestamp: | ||
return decodeDatetime(strValue); | ||
case Oid.date: | ||
return decodeDate(strValue); | ||
default: | ||
throw new Error(`Don't know how to parse column type: ${typeOid}`); | ||
} | ||
} | ||
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export function decode(value: Uint8Array, column: Column) { | ||
if (column.format === Format.BINARY) { | ||
return decodeBinary(); | ||
} else if (column.format === Format.TEXT) { | ||
return decodeText(value, column.typeOid); | ||
} else { | ||
throw new Error(`Unknown column format: ${column.format}`); | ||
} | ||
} |
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