Detect when variables are declared and not set

It is possible to declare a variable but not assign a value to it using
`export x`. When you do this, `declare -p x` shows the variable but does
not show an "=" nor any value afterwards.

When running another command, this variable will not be added to the
environment variables even though it is flagged as exported. Most likely
it's because the value is not a string and can't be easily converted to
a string; this is the same behavior as arrays.

Using `[[ -v x ]]` is also inadequate and I believe its because there
are false positives when trying to access data, which goes on to break
tests and the new braces and parenthesis indirection. Perhaps it could
be reviewed and made to work.

The best solution so far is to combine `declare -p` with `[[ -v` to see
if the variable is declared and if a value is set.

Closes #75.

README.md

@@ -265,6 +265,7 @@ Pull requests to solve the following issues would be helpful.
 
 * Dotted names are supported but only for associative arrays (Bash 4).  See [`demo/associative-arrays`](demo/associative-arrays) for an example.
 * There's no "top level" object, so `echo '{{.}}' | ./mo` does not do anything useful.  In other languages you can say the data for the template is a string and in `mo` the data is always the environment.  Luckily this type of usage is rare and `{{.}}` works great when iterating over an array.
+* [Parents](https://mustache.github.io/mustache.5.html#Parents), where a template can override chunks of a partial, are not supported.
 * HTML encoding is not built into `mo`.  `{{{var}}}`, `{{&var}}` and `{{var}}` all do the same thing.  `echo '{{TEST}}' | TEST='<b>' mo` will give you "`<b>`" instead of "`&gt;b&lt;`".
 
 

mo

@@ -115,6 +115,8 @@ mo() (
     moDoubleHyphens=false
     MO_OPEN_DELIMITER_DEFAULT="{{"
     MO_CLOSE_DELIMITER_DEFAULT="}}"
+    MO_FUNCTION_CACHE_HIT=()
+    MO_FUNCTION_CACHE_MISS=()
 
     if [[ $# -gt 0 ]]; then
         for arg in "$@"; do
@@ -430,30 +432,19 @@ mo::indirectArray() {
 #
 # Returns nothing.
 mo::trimUnparsed() {
-    local moLastLen moR moN moT
+    local moI moC
 
-    moLastLen=0
-    moR=$'\r'
-    moN=$'\n'
-    moT=$'\t'
+    moI=0
+    moC=${MO_UNPARSED:0:1}
 
-    while [[ "${#MO_UNPARSED}" != "$moLastLen" ]]; do
-        moLastLen=${#MO_UNPARSED}
-
-        # These conditions are necessary for a significant speed increase
-        while [[ "${MO_UNPARSED:0:1}" == " " ]]; do 
-            MO_UNPARSED=${MO_UNPARSED# }
-        done
-        while [[ "${MO_UNPARSED:0:1}" == "$moR" ]]; do
-            MO_UNPARSED=${MO_UNPARSED#"$moR"}
-        done
-        while [[ "${MO_UNPARSED:0:1}" == "$moN" ]]; do
-            MO_UNPARSED=${MO_UNPARSED#"$moN"}
-        done
-        while [[ "${MO_UNPARSED:0:1}" == "$moT" ]]; do
-            MO_UNPARSED=${MO_UNPARSED#"$moT"}
-        done
+    while [[ "$moC" == " " || "$moC" == $'\r' || "$moC" == $'\n' || "$moC" == $'\t' ]]; do
+        moI=$((moI + 1))
+        moC=${MO_UNPARSED:$moI:1}
     done
+
+    if [[ "$moI" != 0 ]]; then
+        MO_UNPARSED=${MO_UNPARSED:$moI}
+    fi
 }
 
 
@@ -911,10 +902,28 @@ mo::parseValue() {
 #
 # Returns 0 if the name is a function, 1 otherwise.
 mo::isFunction() {
+    local moFunctionName
+
+    for moFunctionName in "${MO_FUNCTION_CACHE_HIT[@]}"; do
+        if [[ "$moFunctionName" == "$1" ]]; then
+            return 0
+        fi
+    done
+
+    for moFunctionName in "${MO_FUNCTION_CACHE_MISS[@]}"; do
+        if [[ "$moFunctionName" == "$1" ]]; then
+            return 1
+        fi
+    done
+
     if declare -F "$1" &> /dev/null; then
+        MO_FUNCTION_CACHE_HIT=( ${MO_FUNCTION_CACHE_HIT[@]+"${MO_FUNCTION_CACHE_HIT[@]}"} "$1" )
+
         return 0
     fi
 
+    MO_FUNCTION_CACHE_MISS=( ${MO_FUNCTION_CACHE_MISS[@]+"${MO_FUNCTION_CACHE_MISS[@]}"} "$1" )
+
     return 1
 }
 
@@ -993,13 +1002,24 @@ mo::isArrayIndexValid() {
 # Can not use logic like this in case invalid variable names are passed.
 #     [[ "${!1-a}" == "${!1-b}" ]]
 #
+# Using logic like this gives false positives.
+#     [[ -v "$a" ]]
+#
+# Declaring a variable is not the same as assigning the variable.
+#     export x
+#     declare -p x   # Output: declare -x x
+#     export y=""
+#     declare -p y   # Output: declare -x y=""
+#     unset z
+#     declare -p z   # Error code 1 and output: bash: declare: z: not found
+#
 # Returns true (0) if the variable is set, 1 if the variable is unset.
 mo::isVarSet() {
-    if ! declare -p "$1" &> /dev/null; then
-        return 1
+    if declare -p "$1" &> /dev/null && [[ -v "$1" ]]; then
+        return 0
     fi
 
-    return 0
+    return 1
 }
 
 
@@ -1410,31 +1430,39 @@ mo::standaloneCheck() {
 #
 # Returns nothing.
 mo::standaloneProcess() {
-    local moContent moLast moT moR moN
-
-    moT=$'\t'
-    moR=$'\r'
-    moN=$'\n'
-    moLast=
+    local moI moTemp
 
     mo::debug "Standalone tag - processing content before and after tag"
+    moI=$((${#MO_PARSED} - 1))
+    mo::debug "zero done ${#MO_PARSED}"
+    mo::escape moTemp "$MO_PARSED"
+    mo::debug "$moTemp"
 
-    while [[ "$moLast" != "$MO_PARSED" ]]; do
-        moLast=$MO_PARSED
-        MO_PARSED=${MO_PARSED% }
-        MO_PARSED=${MO_PARSED%"$moT"}
+    while [[ "${MO_PARSED:$moI:1}" == " " || "${MO_PARSED:$moI:1}" == $'\t' ]]; do
+        moI=$((moI - 1))
     done
 
-    moLast=
+    if [[ $((moI + 1)) != "${#MO_PARSED}" ]]; then
+        MO_PARSED="${MO_PARSED:0:${moI}+1}"
+    fi
 
-    while [[ "$moLast" != "$MO_UNPARSED" ]]; do
-        moLast=$MO_UNPARSED
-        MO_UNPARSED=${MO_UNPARSED# }
-        MO_UNPARSED=${MO_UNPARSED#"$moT"}
+    moI=0
+
+    while [[ "${MO_UNPARSED:${moI}:1}" == " " || "${MO_UNPARSED:${moI}:1}" == $'\t' ]]; do
+        moI=$((moI + 1))
     done
 
-    MO_UNPARSED=${MO_UNPARSED#"$moR"}
-    MO_UNPARSED=${MO_UNPARSED#"$moN"}
+    if [[ "${MO_UNPARSED:${moI}:1}" == $'\r' ]]; then
+        moI=$((moI + 1))
+    fi
+
+    if [[ "${MO_UNPARSED:${moI}:1}" == $'\n' ]]; then
+        moI=$((moI + 1))
+    fi
+
+    if [[ "$moI" != 0 ]]; then
+        MO_UNPARSED=${MO_UNPARSED:${moI}}
+    fi
 }
 
 
@@ -1960,7 +1988,7 @@ mo::tokenizeTagContentsSingleQuote() {
 
 # Save the original command's path for usage later
 MO_ORIGINAL_COMMAND="$(cd "${BASH_SOURCE[0]%/*}" || exit 1; pwd)/${BASH_SOURCE[0]##*/}"
-MO_VERSION="3.0.5"
+MO_VERSION="3.0.7"
 
 # If sourced, load all functions.
 # If executed, perform the actions as expected.

tests/help

@@ -94,7 +94,7 @@ This is open source!  Please feel free to contribute.
 
 https://github.com/tests-always-included/mo
 
-MO_VERSION=3.0.5
+MO_VERSION=3.0.7
 EOF
 }
 

tests/issue-75

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+cd "${0%/*}" || exit 1
+. ../run-tests
+
+export uv
+export template='{{^uv}}OK{{/uv}}{{#uv}}FAIL{{/uv}}'
+export expected='OK'
+
+runTest