Make it work on macOS (#7)

* Document how to run on macOS, which is a BSD system

* Fix padding to work on BSD

Generated via `sed -i'' -e 's/%0${indent}s/%${indent}s/' JSONPath.sh`.

Implementations seem to deviate here. For % with the 0 flag character, Linux states

> The value should be zero padded. For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, the converted value is padded on the left with zeros rather than blanks.

while BSD states

> A zero `0' character indicating that zero-padding should be used rather than blank-padding.

Author: cburgmer

JSONPath.sh

@@ -659,7 +659,7 @@ json() {
               arrays[j]=
               [[ -n ${closers[j]} ]] && {
                 let indent=j*4
-                printf "\n%0${indent}s${closers[j]}" ""
+                printf "\n%${indent}s${closers[j]}" ""
                 unset closers[j]
                 comma[j]=
               }
@@ -673,7 +673,7 @@ json() {
             arrays[j]=
             [[ -n ${closers[j]} ]] && {
               let indent=j*4
-              printf "\n%0${indent}s${closers[j]}" ""
+              printf "\n%${indent}s${closers[j]}" ""
               unset closers[j]
               comma[j]=
             }
@@ -695,7 +695,7 @@ json() {
           arrays[i]=
           [[ -n ${closers[i]} ]] && {
             let indent=i*4
-            printf "\n%0${indent}s${closers[i]}" ""
+            printf "\n%${indent}s${closers[i]}" ""
             unset closers[i]
             comma[i]=
           }
@@ -721,25 +721,25 @@ json() {
           # Object
           [[ $i -ge $broken ]] && {
             let indent=i*4
-            printf "${comma[i]}%0${indent}s{\n" ""
+            printf "${comma[i]}%${indent}s{\n" ""
             closers[i]='}'
             comma[i]=
           }
           let indent=(i+1)*4
-          printf "${comma[i]}%0${indent}s${path[i]}:\n" ""
+          printf "${comma[i]}%${indent}s${path[i]}:\n" ""
           comma[i]=",\n"
         else
           # Array
           if [[ ${arrays[i]} != 1 ]]; then
             let indent=i*4
-            printf "%0${indent}s" ""
+            printf "%${indent}s" ""
             echo "["
             closers[i]=']'
             arrays[i]=1
             comma[i]=
           else
             let indent=(i+1)*4
-            printf "\n%0${indent}s${closers[i-1]}" ""
+            printf "\n%${indent}s${closers[i-1]}" ""
             direction=$DOWN
             comma[i+1]=",\n"
           fi
@@ -752,25 +752,25 @@ json() {
         # Object
         [[ $direction -eq $DOWN ]] && {
           let indent=pathlen*4
-          printf "${comma[pathlen]}%0${indent}s{\n" ""
+          printf "${comma[pathlen]}%${indent}s{\n" ""
           closers[pathlen]='}'
           comma[pathlen]=
         }
         let indent=(pathlen+1)*4
-        printf "${comma[pathlen]}%0${indent}s" ""
+        printf "${comma[pathlen]}%${indent}s" ""
         echo -n "${path[-1]}:$value"
         comma[pathlen]=",\n"
       else
         # Array
         [[ ${arrays[i]} != 1 ]] && {
           let indent=(pathlen-0)*4
-          printf "%0${indent}s[\n" ""
+          printf "%${indent}s[\n" ""
           closers[pathlen]=']'
           comma[pathlen]=
           arrays[i]=1
         }
         let indent=(pathlen+1)*4
-        printf "${comma[pathlen]}%0${indent}s" ""
+        printf "${comma[pathlen]}%${indent}s" ""
         echo -n "$value"
         comma[pathlen]=",\n"
       fi
@@ -784,7 +784,7 @@ json() {
     for i in `seq $((pathlen)) -1 0`
     do
       let indent=i*4
-      printf "\n%0${indent}s${closers[i]}" ""
+      printf "\n%${indent}s${closers[i]}" ""
     done
     echo
   fi

README.md

@@ -4,6 +4,9 @@ yo, so it's a JSONPath implementation written in Bash - and it probably only wor
 
 [![travis](https://secure.travis-ci.org/mclarkson/JSONPath.sh.png?branch=master)](https://travis-ci.org/mclarkson/JSONPath.sh)
 
+Currently we rely on GNU implementations of the underlying tools. On OSX you can
+try wrapping the command like `./ensure_deps.sh ./JSONPath.sh`.
+
 ## Invocation
 
     JSONPath.sh [-b] [-i] [-j] [-h] [-p] [-u] [-f FILE] [pattern]
@@ -67,7 +70,7 @@ $ ./JSONPath.sh < package.json
 ["repository","url"]    "https://github.com/mclarkson/JSONPath.sh.git"
 ["bin","JSONPath.sh"]   "./JSONPath.sh"
 ["author"]      "Mark Clarkson <mark.clarkson@smorg.co.uk>"
-["scripts","test"]      "./all-tests.sh"
+["scripts","test"]      "./ensure_deps.sh ./all-tests.sh"
 ```
 
 more complex examples:

ensure_deps.sh

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+is_osx() {
+    test "$(uname -s)" == "Darwin"
+}
+
+test_gnu_compat() {
+    local error=0
+    if ! seq 0 -1 1 &> /dev/null; then
+        error=1
+        >&2 echo "Make sure you have GNU coreutils installed"
+    fi
+
+    if grep --version | grep 'BSD' &> /dev/null; then
+        error=1
+        >&2 echo "Make sure you have GNU grep or compatible installed"
+    fi
+
+    if ! sed --version &> /dev/null; then
+        error=1
+        >&2 echo "Make sure you have GNU sed or compatible installed"
+    fi
+
+    if [[ $error -gt 0 && is_osx ]]; then
+        >&2 echo "With homebrew you may install necessary deps via \`brew install grep gnu-sed coreutils\`"
+    fi
+
+    return $error
+}
+
+main() {
+    if is_osx; then
+        export PATH="/usr/local/opt/coreutils/libexec/gnubin:$PATH"
+        export PATH="/usr/local/opt/grep/libexec/gnubin:$PATH"
+        export PATH="/usr/local/opt/gnu-sed/libexec/gnubin:$PATH"
+    fi
+
+    test_gnu_compat
+
+    "$@"
+}
+
+main "$@"

package.json

@@ -14,6 +14,6 @@
   "devDependencies": {},
   "author": "Mark Clarkson <mark.clarkson@smorg.co.uk>",
   "scripts": {
-    "test": "./all-tests.sh"
+    "test": "./ensure_deps.sh ./all-tests.sh"
   }
 }