;;; metar.el --- Retrieve and decode METAR weather information
-;; Copyright (C) 2007, 2014 Free Software Foundation, Inc.
+;; Copyright (C) 2007, 2014-2016 Free Software Foundation, Inc.
;; Author: Mario Lang <mlang@delysid.org>
-;; Version: 0.1
+;; Version: 0.2
;; Package-Requires: ((cl-lib "0.5"))
;; Keywords: comm
(when station-code
(cons station-code (round best-distance))))))
-(defun metar-convert-unit (value new-unit)
+(defun metar-convert-unit (value new-unit &optional convert-units-function)
"Convert VALUE to NEW-UNIT.
VALUE is a string with the value followed by the unit, like \"5 knot\"
-and NEW-UNIT should be a unit name like \"kph\" or similar."
+and NEW-UNIT should be a unit name like \"kph\" or similar.
+CONVERT-UNITS-FUNCTION designates the function actually doing the conversion.
+It must have the signature of `math-convert-units', which is the default."
(cl-check-type value string)
- (cl-check-type new-unit (or string symbol))
- (cl-multiple-value-bind (value unit)
- (split-string
- (math-format-value
- (math-convert-units (math-simplify (math-read-expr value))
- (math-read-expr
- (cl-etypecase new-unit
- (string new-unit)
- (symbol (symbol-name new-unit))))))
- " ")
- (cons (string-to-number value) (intern unit))))
+ (unless (symbolp new-unit)
+ (setq new-unit (intern new-unit)))
+ (let ((expr (math-simplify (math-read-expr value))))
+ ;; Sneakily work around bug#19582.
+ (when (eq (car-safe expr) 'neg)
+ (setq expr `(* -1 ,(cadr expr))))
+ (cl-assert (or (math-zerop expr)
+ (not (memq (math-single-units-in-expr-p expr) '(nil wrong))))
+ nil
+ "Metar: Not exactly one unit in expression: %S" expr)
+ (let ((res (math-simplify-units
+ (funcall (or convert-units-function 'math-convert-units)
+ expr
+ (math-build-var-name new-unit)
+ t))))
+ (cl-assert (math-realp res) nil
+ "Metar: Not a Calc real number: %S" res)
+ (cons (string-to-number (math-format-value (if (integerp res)
+ res
+ (math-float res))))
+ new-unit))))
(defun metar-convert-temperature (string &optional unit)
- (let* ((value (concat (if (= (aref string 0) ?M)
- (concat "-" (substring string 1))
- string)
- "degC"))
- (expr (math-read-expr value))
- (old-unit (math-single-units-in-expr-p expr))
- (new-unit (or unit (cdr (assq 'temperature metar-units)))))
- (if old-unit
- (cl-multiple-value-bind (value unit)
- (split-string
- (math-format-value
- (math-simplify-units
- (math-convert-temperature
- expr
- (list 'var
- (car old-unit)
- (intern (concat "var-" (symbol-name (car old-unit)))))
- (math-read-expr (cl-etypecase new-unit
- (string new-unit)
- (symbol (symbol-name new-unit))))))) " ")
- (cons (string-to-number value) (intern unit))))))
+ (metar-convert-unit (concat (if (= (aref string 0) ?M)
+ (concat "-" (substring string 1))
+ string)
+ "degC")
+ (or unit (cdr (assq 'temperature metar-units)))
+ (lambda (expr new-unit-var pure)
+ (math-convert-temperature expr
+ (math-build-var-name 'degC)
+ new-unit-var
+ pure))))
(defcustom metar-url
"http://weather.noaa.gov/pub/data/observations/metar/stations/%s.TXT"