Move the Gaeval parser to its own file (#304)

Whether this belongs in the `galgebra.printer` namespace at all is a different question, to be addressed another time.

Author: eric-wieser

galgebra/_utils/parser.py

@@ -0,0 +1,168 @@
+""" A private module to parse multivector expressions """
+import re
+
+op_cntrct = re.compile(r'(([A-Za-z0-9\_\#]+)(\||<|>)([A-Za-z0-9\_\#]+))')
+op_wedge = re.compile(r'(([A-Za-z0-9\_\#]+)[\^]{1}([A-Za-z0-9\_\#]+)([\^]{1}([A-Za-z0-9\_\#]+))*)')
+ops = r'[\^\|\<\>]+'
+ops_search = re.compile(r'(\^|\||<|>)+')
+parse_paren_calls = 0
+op_dict = {}
+op_lst = []
+
+OPS = {'<>|': r'(([A-Za-z0-9\_\#]+)(\||<|>)([A-Za-z0-9\_\#]+))',
+       '^': r'(([A-Za-z0-9\_\#]+)[\^]{1}([A-Za-z0-9\_\#]+)([\^]{1}([A-Za-z0-9\_\#]+))*)',
+       '*': r'(([A-Za-z0-9\_\#]+)[\*]{1}([A-Za-z0-9\_\#]+)([\*]{1}([A-Za-z0-9\_\#]+))*)'}
+
+
+def set_precedence(op_ord: str = '<>|,^,*') -> None:
+    global op_dict, op_lst
+    op_lst = op_ord.split(',')
+    op_dict = {}
+    for op in op_lst:
+        op_dict[op] = re.compile(OPS[op])
+
+
+def _contains_interval(interval1, interval2):  # interval1 inside interval2
+    if interval1[0] > interval2[0] and interval1[1] < interval2[1]:
+        return True
+    else:
+        return False
+
+
+def _parse_paren(line):
+    global parse_paren_calls
+    parse_paren_calls += 1
+
+    if ('(' not in line) or (')' not in line):
+        return [[[line]]]
+    level = 0
+    max_level = 0
+    ich = 0
+    paren_lst = []
+    for ch in line:
+        if ch == '(':
+            level += 1
+            paren_lst.append([level, ich])
+        if ch == ')':
+            if level < 1:
+                raise ValueError('Mismathed Parenthesis in: ' + line + '\n')
+            paren_lst.reverse()
+            iparen = 0
+            for elem in paren_lst:
+                if elem[0] == level:
+                    paren_lst[iparen].append(ich)
+                    break
+                iparen += 1
+            paren_lst.reverse()
+            level -= 1
+        max_level = max(max_level, level)
+        ich += 1
+    if level != 0:
+        raise ValueError('Mismatched Parenthesis in: ' + line + '\n')
+    if max_level > 0:
+        level_lst = []
+        for _x in range(max_level + 1):
+            level_lst.append([])
+        for group in paren_lst:
+            level_lst[group[0]].append(group[1:])
+        ilevel = max_level
+        while ilevel > 1:
+            level = level_lst[ilevel]
+            level_down = level_lst[ilevel - 1]
+            igroup = 0
+            for group in level:
+                igroup_down = 0
+                for group_down in level_down:
+                    if _contains_interval(group, group_down):
+                        level_lst[ilevel][igroup].append(igroup_down)
+                    igroup_down += 1
+                igroup += 1
+            ilevel -= 1
+        ilevel = 1
+        for level in level_lst[1:]:
+            igroup = 0
+            for group in level:
+                token = '#' + str(parse_paren_calls) + '_' + str(ilevel) + '_' + str(igroup) + '#'
+                level_lst[ilevel][igroup].append(line[group[0]:group[1] + 1])
+                level_lst[ilevel][igroup].append(token)
+                igroup += 1
+            ilevel += 1
+        ilevel = 1
+        for level in level_lst[1:]:
+            igroup = 0
+            for group in level:
+                group.append(group[-2])
+                level_lst[ilevel][igroup] = group
+                igroup += 1
+            ilevel += 1
+        ilevel = max_level
+        while ilevel > 1:
+            igroup = 0
+            for group in level_lst[ilevel]:
+                group_down = level_lst[ilevel - 1][group[2]]
+                replace_text = group_down[-1].replace(group[-3], group[-2])
+                level_lst[ilevel - 1][group[2]][-1] = replace_text
+                igroup += 1
+            ilevel -= 1
+        for group in level_lst[1]:
+            line = line.replace(group[2], group[3])
+        ilevel = 1
+        level_lst[0] = [[line]]
+    return level_lst
+
+
+def _unparse_paren(level_lst):
+    line = level_lst[0][0][0]
+    for level in level_lst[1:]:
+        for group in level:
+            new_string = group[-1]
+            if new_string[:2] == '((' and new_string[-2:] == '))':
+                new_string = new_string[1:-1]
+            line = line.replace(group[-2], new_string)
+    return line
+
+
+def _sub_paren(s):
+    string = s.group(0)
+    return '(%s)' % string
+
+
+def _add_paren(line, re_exprs):
+    paren_flg = False
+    if (line[0] == '(') and (line[-1] == ')'):
+        paren_flg = True
+        line = line[1:-1]
+    if ('(' in line) or (')' in line):
+        line_levels = _parse_paren(line)
+        ilevel = 0
+        for level in line_levels:
+            igroup = 0
+            for group in level:
+                group[-1] = re.sub(re_exprs, _sub_paren, group[-1])
+                line_levels[ilevel][igroup] = group
+                igroup += 1
+            ilevel += 1
+        line = _unparse_paren(line_levels)
+    else:
+        line = re.sub(re_exprs, _sub_paren, line)
+    if paren_flg:
+        line = '(' + line + ')'
+    return line
+
+
+def parse_line(line: str) -> str:
+    global op_lst, op_dict
+    line = line.replace(' ', '')
+    level_lst = _parse_paren(line)
+    ilevel = 0
+    for level in level_lst:
+        igroup = 0
+        for group in level:
+            string = group[-1]
+            for op in op_lst:
+                string = _add_paren(string, op_dict[op])
+            level_lst[ilevel][igroup][-1] = string
+            igroup += 1
+        ilevel += 1
+    line = _unparse_paren(level_lst)
+    return line

galgebra/printer.py

@@ -5,7 +5,6 @@
 import os
 import sys
 import io
-import re
 import builtins
 import functools
 from sympy import Matrix, Basic, S, Symbol, Function, Derivative, Pow
@@ -27,6 +26,8 @@
 
 from inspect import getouterframes, currentframe
 
+from ._utils import parser as _parser
+
 ZERO_STR = ' 0 '
 
 Format_cnt = 0
@@ -1181,18 +1182,7 @@ def Print_Function():
     return
 
 
-op_cntrct = re.compile(r'(([A-Za-z0-9\_\#]+)(\||<|>)([A-Za-z0-9\_\#]+))')
-op_wedge = re.compile(r'(([A-Za-z0-9\_\#]+)[\^]{1}([A-Za-z0-9\_\#]+)([\^]{1}([A-Za-z0-9\_\#]+))*)')
-ops = r'[\^\|\<\>]+'
-ops_search = re.compile(r'(\^|\||<|>)+')
-parse_paren_calls = 0
 global_dict = {}
-op_dict = {}
-op_lst = []
-
-OPS = {'<>|': r'(([A-Za-z0-9\_\#]+)(\||<|>)([A-Za-z0-9\_\#]+))',
-       '^': r'(([A-Za-z0-9\_\#]+)[\^]{1}([A-Za-z0-9\_\#]+)([\^]{1}([A-Za-z0-9\_\#]+))*)',
-       '*': r'(([A-Za-z0-9\_\#]+)[\*]{1}([A-Za-z0-9\_\#]+)([\*]{1}([A-Za-z0-9\_\#]+))*)'}
 
 
 def def_prec(gd: dict, op_ord: str = '<>|,^,*') -> None:
@@ -1207,159 +1197,9 @@ def def_prec(gd: dict, op_ord: str = '<>|,^,*') -> None:
         The order of operator precedence from high to low with groups of equal precedence separated by commas.
         The default precedence, ``'<>|,^,*'``, is that used by Hestenes (:cite:`Hestenes`, p7, :cite:`Doran`, p38).
     """
-    global global_dict, op_dict, op_lst
+    global global_dict
     global_dict = gd
-    op_lst = op_ord.split(',')
-    op_dict = {}
-    for op in op_lst:
-        op_dict[op] = re.compile(OPS[op])
-    return
-
-
-def contains_interval(interval1, interval2):  # interval1 inside interval2
-    if interval1[0] > interval2[0] and interval1[1] < interval2[1]:
-        return True
-    else:
-        return False
-
-
-def parse_paren(line):
-    global parse_paren_calls
-    parse_paren_calls += 1
-
-    if ('(' not in line) or (')' not in line):
-        return [[[line]]]
-    level = 0
-    max_level = 0
-    ich = 0
-    paren_lst = []
-    for ch in line:
-        if ch == '(':
-            level += 1
-            paren_lst.append([level, ich])
-        if ch == ')':
-            if level < 1:
-                raise ValueError('Mismathed Parenthesis in: ' + line + '\n')
-            paren_lst.reverse()
-            iparen = 0
-            for elem in paren_lst:
-                if elem[0] == level:
-                    paren_lst[iparen].append(ich)
-                    break
-                iparen += 1
-            paren_lst.reverse()
-            level -= 1
-        max_level = max(max_level, level)
-        ich += 1
-    if level != 0:
-        raise ValueError('Mismatched Parenthesis in: ' + line + '\n')
-    if max_level > 0:
-        level_lst = []
-        for _x in range(max_level + 1):
-            level_lst.append([])
-        for group in paren_lst:
-            level_lst[group[0]].append(group[1:])
-        ilevel = max_level
-        while ilevel > 1:
-            level = level_lst[ilevel]
-            level_down = level_lst[ilevel - 1]
-            igroup = 0
-            for group in level:
-                igroup_down = 0
-                for group_down in level_down:
-                    if contains_interval(group, group_down):
-                        level_lst[ilevel][igroup].append(igroup_down)
-                    igroup_down += 1
-                igroup += 1
-            ilevel -= 1
-        ilevel = 1
-        for level in level_lst[1:]:
-            igroup = 0
-            for group in level:
-                token = '#' + str(parse_paren_calls) + '_' + str(ilevel) + '_' + str(igroup) + '#'
-                level_lst[ilevel][igroup].append(line[group[0]:group[1] + 1])
-                level_lst[ilevel][igroup].append(token)
-                igroup += 1
-            ilevel += 1
-        ilevel = 1
-        for level in level_lst[1:]:
-            igroup = 0
-            for group in level:
-                group.append(group[-2])
-                level_lst[ilevel][igroup] = group
-                igroup += 1
-            ilevel += 1
-        ilevel = max_level
-        while ilevel > 1:
-            igroup = 0
-            for group in level_lst[ilevel]:
-                group_down = level_lst[ilevel - 1][group[2]]
-                replace_text = group_down[-1].replace(group[-3], group[-2])
-                level_lst[ilevel - 1][group[2]][-1] = replace_text
-                igroup += 1
-            ilevel -= 1
-        for group in level_lst[1]:
-            line = line.replace(group[2], group[3])
-        ilevel = 1
-        level_lst[0] = [[line]]
-    return level_lst
-
-
-def unparse_paren(level_lst):
-    line = level_lst[0][0][0]
-    for level in level_lst[1:]:
-        for group in level:
-            new_string = group[-1]
-            if new_string[:2] == '((' and new_string[-2:] == '))':
-                new_string = new_string[1:-1]
-            line = line.replace(group[-2], new_string)
-    return line
-
-
-def sub_paren(s):
-    string = s.group(0)
-    return '(%s)' % string
-
-
-def add_paren(line, re_exprs):
-    paren_flg = False
-    if (line[0] == '(') and (line[-1] == ')'):
-        paren_flg = True
-        line = line[1:-1]
-    if ('(' in line) or (')' in line):
-        line_levels = parse_paren(line)
-        ilevel = 0
-        for level in line_levels:
-            igroup = 0
-            for group in level:
-                group[-1] = re.sub(re_exprs, sub_paren, group[-1])
-                line_levels[ilevel][igroup] = group
-                igroup += 1
-            ilevel += 1
-        line = unparse_paren(line_levels)
-    else:
-        line = re.sub(re_exprs, sub_paren, line)
-    if paren_flg:
-        line = '(' + line + ')'
-    return line
-
-
-def parse_line(line):
-    global op_lst, op_dict
-    line = line.replace(' ', '')
-    level_lst = parse_paren(line)
-    ilevel = 0
-    for level in level_lst:
-        igroup = 0
-        for group in level:
-            string = group[-1]
-            for op in op_lst:
-                string = add_paren(string, op_dict[op])
-            level_lst[ilevel][igroup][-1] = string
-            igroup += 1
-        ilevel += 1
-    line = unparse_paren(level_lst)
-    return line
+    _parser.set_precedence(op_ord)
 
 
 def GAeval(s: str, pstr: bool = False):
@@ -1379,12 +1219,13 @@ def GAeval(s: str, pstr: bool = False):
         enforce operator precedence are printed.
     """
 
-    seval = parse_line(s)
+    seval = _parser.parse_line(s)
     if pstr:
         print(s)
         print(seval)
     return eval(seval, global_dict)
 
+
 r"""
 \begin{array}{c}
 \left ( \begin{array}{c} F,\\ \end{array} \right . \\