1 | # args.ysh
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2 | #
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3 | # Usage:
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4 | # source --builtin args.sh
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5 | #
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6 | # parser (&spec) {
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7 | # flag -v --verbose (help="Verbosely") # default is Bool, false
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8 | #
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9 | # flag -P --max-procs ('int', default=-1, doc='''
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10 | # Run at most P processes at a time
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11 | # ''')
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12 | #
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13 | # flag -i --invert ('bool', default=true, doc='''
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14 | # Long multiline
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15 | # Description
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16 | # ''')
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17 | #
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18 | # arg src (help='Source')
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19 | # arg dest (help='Dest')
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20 | # arg times (help='Foo')
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21 | #
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22 | # rest files
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23 | # }
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24 | #
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25 | # var args = parseArgs(spec, ARGV)
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26 | #
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27 | # echo "Verbose $[args.verbose]"
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28 |
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29 | # TODO: See list
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30 | # - It would be nice to keep `flag` and `arg` private, injecting them into the
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31 | # proc namespace only within `Args`
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32 | # - We need "type object" to replace the strings 'int', 'bool', etc.
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33 | # - flag builtin:
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34 | # - handle only long flag or only short flag
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35 | # - flag aliases
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36 |
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37 | proc parser (; place ; ; block_def) {
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38 | ## Create an args spec which can be passed to parseArgs.
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39 | ##
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40 | ## Example:
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41 | ##
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42 | ## # NOTE: &spec will create a variable named spec
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43 | ## parser (&spec) {
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44 | ## flag -v --verbose ('bool')
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45 | ## }
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46 | ##
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47 | ## var args = parseArgs(spec, ARGV)
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48 |
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49 | var p = {flags: [], args: []}
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50 | ctx push (p; ; block_def)
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51 |
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52 | # Validate that p.rest = [name] or null and reduce p.rest into name or null.
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53 | if ('rest' in p) {
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54 | if (len(p.rest) > 1) {
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55 | error '`rest` was called more than once' (code=3)
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56 | } else {
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57 | setvar p.rest = p.rest[0]
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58 | }
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59 | } else {
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60 | setvar p.rest = null
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61 | }
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62 |
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63 | var names = {}
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64 | for items in ([p.flags, p.args]) {
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65 | for x in (items) {
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66 | if (x.name in names) {
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67 | error "Duplicate flag/arg name $[x.name] in spec" (code=3)
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68 | }
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69 |
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70 | setvar names[x.name] = null
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71 | }
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72 | }
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73 |
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74 | # TODO: what about `flag --name` and then `arg name`?
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75 |
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76 | call place->setValue(p)
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77 | }
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78 |
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79 | proc flag (short, long ; type='bool' ; default=null, help=null) {
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80 | ## Declare a flag within an `arg-parse`.
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81 | ##
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82 | ## Examples:
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83 | ##
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84 | ## arg-parse (&spec) {
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85 | ## flag -v --verbose
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86 | ## flag -n --count ('int', default=1)
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87 | ## flag -f --file ('str', help="File to process")
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88 | ## }
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89 |
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90 | # bool has a default of false, not null
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91 | if (type === 'bool' and default === null) {
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92 | setvar default = false
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93 | }
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94 |
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95 | # TODO: validate `type`
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96 |
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97 | # TODO: Should use "trimPrefix"
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98 | var name = long[2:]
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99 |
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100 | ctx emit flags ({short, long, name, type, default, help})
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101 | }
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102 |
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103 | proc arg (name ; ; help=null) {
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104 | ## Declare a positional argument within an `arg-parse`.
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105 | ##
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106 | ## Examples:
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107 | ##
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108 | ## arg-parse (&spec) {
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109 | ## arg name
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110 | ## arg config (help="config file path")
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111 | ## }
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112 |
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113 | ctx emit args ({name, help})
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114 | }
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115 |
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116 | proc rest (name) {
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117 | ## Take the remaining positional arguments within an `arg-parse`.
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118 | ##
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119 | ## Examples:
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120 | ##
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121 | ## arg-parse (&grepSpec) {
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122 | ## arg query
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123 | ## rest files
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124 | ## }
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125 |
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126 | # We emit instead of set to detect multiple invocations of "rest"
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127 | ctx emit rest (name)
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128 | }
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129 |
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130 | func parseArgs(spec, argv) {
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131 | ## Given a spec created by `parser`. Parse an array of strings `argv` per
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132 | ## that spec.
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133 | ##
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134 | ## See `parser` for examples of use.
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135 |
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136 | var i = 0
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137 | var positionalPos = 0
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138 | var argc = len(argv)
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139 | var args = {}
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140 | var rest = []
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141 |
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142 | var value
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143 | var found
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144 | while (i < argc) {
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145 | var arg = argv[i]
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146 | if (arg->startsWith('-')) {
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147 | setvar found = false
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148 |
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149 | for flag in (spec.flags) {
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150 | if ( (flag.short and flag.short === arg) or
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151 | (flag.long and flag.long === arg) ) {
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152 | case (flag.type) {
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153 | ('bool') | (null) { setvar value = true }
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154 | int {
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155 | setvar i += 1
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156 | if (i >= len(argv)) {
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157 | error "Expected integer after '$arg'" (code=2)
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158 | }
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159 |
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160 | try { setvar value = int(argv[i]) }
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161 | if (_status !== 0) {
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162 | error "Expected integer after '$arg', got '$[argv[i]]'" (code=2)
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163 | }
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164 | }
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165 | }
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166 |
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167 | setvar args[flag.name] = value
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168 | setvar found = true
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169 | break
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170 | }
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171 | }
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172 |
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173 | if (not found) {
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174 | error "Unknown flag '$arg'" (code=2)
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175 | }
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176 | } elif (positionalPos >= len(spec.args)) {
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177 | if (not spec.rest) {
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178 | error "Too many arguments, unexpected '$arg'" (code=2)
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179 | }
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180 |
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181 | call rest->append(arg)
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182 | } else {
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183 | var pos = spec.args[positionalPos]
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184 | setvar positionalPos += 1
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185 | setvar value = arg
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186 | setvar args[pos.name] = value
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187 | }
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188 |
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189 | setvar i += 1
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190 | }
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191 |
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192 | if (spec.rest) {
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193 | setvar args[spec.rest] = rest
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194 | }
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195 |
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196 | # Set defaults for flags
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197 | for flag in (spec.flags) {
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198 | if (flag.name not in args) {
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199 | setvar args[flag.name] = flag.default
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200 | }
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201 | }
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202 |
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203 | # Raise error on missing args
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204 | for arg in (spec.args) {
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205 | if (arg.name not in args) {
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206 | error "Usage Error: Missing required argument $[arg.name]" (code=2)
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207 | }
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208 | }
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209 |
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210 | return (args)
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211 | }
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