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<!doctype html>

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<title>CodeMirror: Ruby mode</title>

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<style>

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.CodeMirror {border-top: 1px solid black; border-bottom: 1px solid black;}

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.cm-s-default span.cm-arrow { color: red; }

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</style>

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<a href="http://codemirror.net"><h1>CodeMirror</h1><img id=logo src="../../doc/logo.png"></a>

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<ul>

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<li><a href="../../doc/manual.html">Manual</a>

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</ul>

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<ul>

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<li><a href="../index.html">Language modes</a>

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</ul>

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</div>

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# Code from http://sandbox.mc.edu/~bennet/ruby/code/poly_rb.html

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# This program evaluates polynomials. It first asks for the coefficients

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# of a polynomial, which must be entered on one line, highest-order first.

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# It then requests values of x and will compute the value of the poly for

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# each x. It will repeatly ask for x values, unless you the user enters

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# a blank line. It that case, it will ask for another polynomial. If the

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# user types quit for either input, the program immediately exits.

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# Function to evaluate a polynomial at x. The polynomial is given

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# as a list of coefficients, from the greatest to the least.

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def polyval(x, coef)

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sum = 0

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coef = coef.clone # Don't want to destroy the original

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while true

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sum += coef.shift # Add and remove the next coef

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break if coef.empty? # If no more, done entirely.

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sum *= x # This happens the right number of times.

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end

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return sum

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end

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# Function to read a line containing a list of integers and return

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# them as an array of integers. If the string conversion fails, it

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# throws TypeError. If the input line is the word 'quit', then it

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# converts it to an end-of-file exception

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def readints(prompt)

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# Read a line

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print prompt

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line = readline.chomp

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raise EOFError.new if line == 'quit' # You can also use a real EOF.

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# Go through each item on the line, converting each one and adding it

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# to retval.

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retval = [ ]

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for str in line.split(/\s+/)

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if str =~ /^\-?\d+$/

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retval.push(str.to_i)

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else

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raise TypeError.new

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end

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end

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return retval

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end

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# Take a coeff and an exponent and return the string representation, ignoring

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# the sign of the coefficient.

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def term_to_str(coef, exp)

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ret = ""

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# Show coeff, unless it's 1 or at the right

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coef = coef.abs

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ret = coef.to_s unless coef == 1 && exp > 0

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ret += "x" if exp > 0 # x if exponent not 0

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ret += "^" + exp.to_s if exp > 1 # ^exponent, if > 1.

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return ret

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end

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# Create a string of the polynomial in sort-of-readable form.

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def polystr(p)

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# Get the exponent of first coefficient, plus 1.

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exp = p.length

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# Assign exponents to each term, making pairs of coeff and exponent,

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# Then get rid of the zero terms.

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p = (p.map { |c| exp -= 1; [ c, exp ] }).select { |p| p[0] != 0 }

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# If there's nothing left, it's a zero

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return "0" if p.empty?

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# *** Now p is a non-empty list of [ coef, exponent ] pairs. ***

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# Convert the first term, preceded by a "-" if it's negative.

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result = (if p[0][0] < 0 then "-" else "" end) + term_to_str(*p[0])

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# Convert the rest of the terms, in each case adding the appropriate

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# + or - separating them.

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for term in p[1...p.length]

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# Add the separator then the rep. of the term.

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result += (if term[0] < 0 then " - " else " + " end) +

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term_to_str(*term)

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end

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return result

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end

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# Run until some kind of endfile.

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begin

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# Repeat until an exception or quit gets us out.

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while true

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# Read a poly until it works. An EOF will except out of the

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# program.

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print "\n"

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begin

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poly = readints("Enter a polynomial coefficients: ")

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rescue TypeError

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print "Try again.\n"

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retry

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end

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break if poly.empty?

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# Read and evaluate x values until the user types a blank line.

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# Again, an EOF will except out of the pgm.

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while true

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# Request an integer.

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print "Enter x value or blank line: "

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x = readline.chomp

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break if x == ''

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raise EOFError.new if x == 'quit'

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# If it looks bad, let's try again.

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if x !~ /^\-?\d+$/

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print "That doesn't look like an integer. Please try again.\n"

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end

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# Convert to an integer and print the result.

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x = x.to_i

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print "p(x) = ", polystr(poly), "\n"

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print "p(", x, ") = ", polyval(x, poly), "\n"

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end

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end

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rescue EOFError

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print "\n=== EOF ===\n"

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rescue Interrupt, SignalException

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print "\n=== Interrupted ===\n"

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else

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print "--- Bye ---\n"

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end

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</textarea></form>

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var editor = CodeMirror.fromTextArea(document.getElementById("code"), {

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mode: "text/x-ruby",

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matchBrackets: true,

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indentUnit: 4

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});

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</script>

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<p><strong>MIME types defined:</strong> <code>text/x-ruby</code>.</p>

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<p>Development of the CodeMirror Ruby mode was kindly sponsored

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by <a href="http://ubalo.com/">Ubalo</a>.</p>

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</article>

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