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1 <!doctype html>
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2
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3 <title>CodeMirror: Ruby mode</title>
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8 <script src="../../lib/codemirror.js"></script>
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9 <script src="../../addon/edit/matchbrackets.js"></script>
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10 <script src="ruby.js"></script>
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11 <style>
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12 .CodeMirror {border-top: 1px solid black; border-bottom: 1px solid black;}
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13 .cm-s-default span.cm-arrow { color: red; }
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14 </style>
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15 <div id=nav>
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16 <a href="https://codemirror.net/5"><h1>CodeMirror</h1><img id=logo src="../../doc/logo.png" alt=""></a>
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17
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18 <ul>
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19 <li><a href="../../index.html">Home</a>
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20 <li><a href="../../doc/manual.html">Manual</a>
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21 <li><a href="https://github.com/codemirror/codemirror5">Code</a>
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22 </ul>
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23 <ul>
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24 <li><a href="../index.html">Language modes</a>
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25 <li><a class=active href="#">Ruby</a>
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26 </ul>
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27 </div>
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28
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29 <article>
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30 <h2>Ruby mode</h2>
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31 <form><textarea id="code" name="code">
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32 # Code from http://sandbox.mc.edu/~bennet/ruby/code/poly_rb.html
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33 #
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34 # This program evaluates polynomials. It first asks for the coefficients
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35 # of a polynomial, which must be entered on one line, highest-order first.
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36 # It then requests values of x and will compute the value of the poly for
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37 # each x. It will repeatedly ask for x values, unless you the user enters
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38 # a blank line. It that case, it will ask for another polynomial. If the
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39 # user types quit for either input, the program immediately exits.
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40 #
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41
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42 #
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43 # Function to evaluate a polynomial at x. The polynomial is given
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44 # as a list of coefficients, from the greatest to the least.
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45 def polyval(x, coef)
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46 sum = 0
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47 coef = coef.clone # Don't want to destroy the original
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48 while true
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49 sum += coef.shift # Add and remove the next coef
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50 break if coef.empty? # If no more, done entirely.
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51 sum *= x # This happens the right number of times.
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52 end
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53 return sum
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54 end
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55
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56 #
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57 # Function to read a line containing a list of integers and return
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58 # them as an array of integers. If the string conversion fails, it
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59 # throws TypeError. If the input line is the word 'quit', then it
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60 # converts it to an end-of-file exception
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61 def readints(prompt)
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62 # Read a line
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63 print prompt
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64 line = readline.chomp
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65 raise EOFError.new if line == 'quit' # You can also use a real EOF.
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66
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67 # Go through each item on the line, converting each one and adding it
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68 # to retval.
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69 retval = [ ]
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70 for str in line.split(/\s+/)
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71 if str =~ /^\-?\d+$/
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72 retval.push(str.to_i)
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73 else
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74 raise TypeError.new
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75 end
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76 end
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77
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78 return retval
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79 end
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80
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81 #
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82 # Take a coeff and an exponent and return the string representation, ignoring
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83 # the sign of the coefficient.
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84 def term_to_str(coef, exp)
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85 ret = ""
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86
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87 # Show coeff, unless it's 1 or at the right
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88 coef = coef.abs
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89 ret = coef.to_s unless coef == 1 && exp > 0
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90 ret += "x" if exp > 0 # x if exponent not 0
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91 ret += "^" + exp.to_s if exp > 1 # ^exponent, if > 1.
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92
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93 return ret
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94 end
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95
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96 #
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97 # Create a string of the polynomial in sort-of-readable form.
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98 def polystr(p)
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99 # Get the exponent of first coefficient, plus 1.
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100 exp = p.length
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101
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102 # Assign exponents to each term, making pairs of coeff and exponent,
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103 # Then get rid of the zero terms.
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104 p = (p.map { |c| exp -= 1; [ c, exp ] }).select { |p| p[0] != 0 }
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105
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106 # If there's nothing left, it's a zero
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107 return "0" if p.empty?
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108
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109 # *** Now p is a non-empty list of [ coef, exponent ] pairs. ***
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110
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111 # Convert the first term, preceded by a "-" if it's negative.
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112 result = (if p[0][0] < 0 then "-" else "" end) + term_to_str(*p[0])
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113
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114 # Convert the rest of the terms, in each case adding the appropriate
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115 # + or - separating them.
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116 for term in p[1...p.length]
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117 # Add the separator then the rep. of the term.
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118 result += (if term[0] < 0 then " - " else " + " end) +
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119 term_to_str(*term)
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120 end
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121
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122 return result
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123 end
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124
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125 #
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126 # Run until some kind of endfile.
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127 begin
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128 # Repeat until an exception or quit gets us out.
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129 while true
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130 # Read a poly until it works. An EOF will except out of the
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131 # program.
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132 print "\n"
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133 begin
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134 poly = readints("Enter a polynomial coefficients: ")
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135 rescue TypeError
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136 print "Try again.\n"
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137 retry
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138 end
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139 break if poly.empty?
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140
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141 # Read and evaluate x values until the user types a blank line.
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142 # Again, an EOF will except out of the pgm.
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143 while true
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144 # Request an integer.
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145 print "Enter x value or blank line: "
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146 x = readline.chomp
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147 break if x == ''
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148 raise EOFError.new if x == 'quit'
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149
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150 # If it looks bad, let's try again.
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151 if x !~ /^\-?\d+$/
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152 print "That doesn't look like an integer. Please try again.\n"
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153 next
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154 end
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155
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156 # Convert to an integer and print the result.
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157 x = x.to_i
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158 print "p(x) = ", polystr(poly), "\n"
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159 print "p(", x, ") = ", polyval(x, poly), "\n"
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160 end
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161 end
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162 rescue EOFError
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163 print "\n=== EOF ===\n"
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164 rescue Interrupt, SignalException
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165 print "\n=== Interrupted ===\n"
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166 else
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167 print "--- Bye ---\n"
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168 end
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169 </textarea></form>
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170 <script>
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171 var editor = CodeMirror.fromTextArea(document.getElementById("code"), {
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172 mode: "text/x-ruby",
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173 matchBrackets: true,
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174 indentUnit: 4
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175 });
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176 </script>
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177
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178 <p><strong>MIME types defined:</strong> <code>text/x-ruby</code>.</p>
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179
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180 <p>Development of the CodeMirror Ruby mode was kindly sponsored
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181 by <a href="http://ubalo.com/">Ubalo</a>.</p>
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182
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183 </article>
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