init

.zprezto/modules/helper/README.md

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+Helper
+======
+
+Provides helper functions for developing modules.
+
+Functions
+---------
+
+  - `add-zsh-trap` adds a function name to a list to be called when a trap is
+    triggered.
+  - `is-autoloadable` checks if a file can be autoloaded by trying to load it
+    in a subshell.
+  - `is-callable` checks if a name is a command, function, or alias.
+  - `is-true` checks a boolean variable for "true".
+  - `coalesce` prints the first non-empty string in the arguments array.
+
+Authors
+-------
+
+*The authors of this module should be contacted via the [issue tracker][1].*
+
+  - [Sorin Ionescu](https://github.com/sorin-ionescu)
+
+[1]: https://github.com/sorin-ionescu/prezto/issues

.zprezto/modules/helper/functions/add-zsh-trap

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+#
+# Provides for trapping UNIX signals and calling callback functions when a trap
+# is triggered.
+#
+# Authors:
+#   Sorin Ionescu <sorin.ionescu@gmail.com>
+#
+
+# Adds a function name to a list to be called when a trap is triggered.
+function add-zsh-trap {
+  if (( $# < 2 )); then
+    print "usage: $0 type function" >&2
+    return 1
+  fi
+
+  if [[ -z "$signals[(r)$1]" ]]; then
+    print "$0: unknown signal: $1" >&2
+    return 1
+  fi
+
+  local trap_functions="TRAP${1}_FUNCTIONS"
+  if (( ! ${(P)+trap_functions} )); then
+    typeset -gaU "$trap_functions"
+  fi
+  eval "$trap_functions+="$2""
+
+  if (( ! $+functions[TRAP${1}] )); then
+    eval "
+      function TRAP${1} {
+        for trap_function in \"\$TRAP${1}_FUNCTIONS[@]\"; do
+          if (( \$+functions[\$trap_function] )); then
+            \"\$trap_function\" \"\$1\"
+          fi
+        done
+        return \$(( 128 + \$1 ))
+      }
+    "
+  fi
+}
+
+add-zsh-trap "$@"

.zprezto/modules/helper/init.zsh

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+#
+# Defines helper functions.
+#
+# Authors:
+#   Sorin Ionescu <sorin.ionescu@gmail.com>
+#
+
+# Checks if a file can be autoloaded by trying to load it in a subshell.
+function is-autoloadable {
+  ( unfunction $1 ; autoload -U +X $1 ) &> /dev/null
+}
+
+# Checks if a name is a command, function, or alias.
+function is-callable {
+  (( $+commands[$1] )) || (( $+functions[$1] )) || (( $+aliases[$1] ))
+}
+
+# Checks a boolean variable for "true".
+# Case insensitive: "1", "y", "yes", "t", "true", "o", and "on".
+function is-true {
+  [[ -n "$1" && "$1" == (1|[Yy]([Ee][Ss]|)|[Tt]([Rr][Uu][Ee]|)|[Oo]([Nn]|)) ]]
+}
+
+# Prints the first non-empty string in the arguments array.
+function coalesce {
+  for arg in $argv; do
+    print "$arg"
+    return 0
+  done
+  return 1
+}