added helper functions for version checker in travis CI

Author: Aaron Soellinger

src/mplfinance/_version.py

@@ -1,6 +1,78 @@
+
+def parse_last_component(last_component_str):
+    """
+    Parse the last component of the version string __version__
+    In:
+        last_component_str: str, last component of version string e.g. for '0.12.3a5' is '3a5'
+    Returns:
+        a: str, e.g. for '3a5' is 3
+        b: str, e.g. for '3a5' is 'alpha'
+        c: str, e.g. for '3a5' is 5
+    """
+    spec_inv = {v:k for k,v in _specifier_.items()}
+    for specifier in _specifier_.values():
+        splt = last_component_str.split(specifier)
+        if len(splt) == 1:
+            continue
+        return int(splt[0]), spec_inv[specifier], int(splt[1])
+    
+
+def parse_version(v_str):
+    """
+    Convert __version__ -> version_info format
+    
+    In:
+        v_str: str, version string e.g. '0.12.3a5'
+        
+    Out:
+        tuple, len == 5; format == version_info (see below)
+    """
+    tmp = v_str.split('.')
+    a,b,c = parse_last_component(tmp[2])
+    return (
+        int(tmp[0]), int(tmp[1]), a, b, c
+    )
+
+
+def compare_versions(v_str1, v_str2):
+    """
+    In:
+        v_str1: str, __version__ string parsable by parse_version
+        v_str2: str, __version__ string parsable by parse_version
+    
+    Returns:
+        '>' | '==' | '<', reads v_str1 (x) v_str2
+    """
+    
+    p_str1 = parse_version(v_str1)
+    p_str2 = parse_version(v_str2)
+    p_str1[3] = _specifier_order_[p_str1[3]]
+    p_str2[3] = _specifier_order_[p_str2[3]]
+    for i, comp_i in enumerate(p_str1):
+        comp_j = p_str2[i]
+        if comp_i > comp_j:
+            return '>'
+        elif comp_i == comp_j:
+            return '=='
+        elif comp_i < comp_j:
+            return '<'
+
+
 version_info = (0, 12, 3, 'alpha', 5)
 
-_specifier_ = {'alpha': 'a', 'beta': 'b', 'candidate': 'rc', 'final': ''}
+_specifier_ = {
+    'alpha': 'a',
+    'beta': 'b',
+    'candidate': 'rc',
+    'final': ''
+}
+
+_specifier_order_ = {
+    'alpha': 1,
+    'beta': 2,
+    'candidate': 3, 
+    'final': 4
+}
 
 __version__ = '%s.%s.%s%s'%(version_info[0], version_info[1], version_info[2],
-  '' if version_info[3]=='final' else _specifier_[version_info[3]]+str(version_info[4]))
+  '' if version_info[3]=='final' else _specifier_[version_info[3]]+str(version_info[4]))