Add a function for getting all items in an expression

Handy e.g. when searching.

4 files changed, 61 insertions, 14 deletions

diff --git a/examples/find_symbol.py b/examples/find_symbol.py
index 55e6345..adc4d73 100644
--- a/examples/find_symbol.py
+++ b/examples/find_symbol.py
@@ -59,7 +59,7 @@
 #   config OPROFILE
 #   ... (tons more lines)
 
-from kconfiglib import Kconfig, Symbol, Choice, MENU, COMMENT, NOT
+from kconfiglib import Kconfig, Symbol, expr_items, Choice, MENU, COMMENT, NOT
 import sys
 
 def expr_contains_sym(expr, sym_name):
@@ -70,18 +70,11 @@ def expr_contains_sym(expr, sym_name):
     Note that "foo" is represented as a constant symbol, like in the C
     implementation.
     """
-    # Choice symbols have a Choice instance propagated to the conditions of
-    # their properties, so we need this test rather than
-    # isinstance(expr, Symbol)
-    if not isinstance(expr, tuple):
-        return expr.name == sym_name
-
-    if expr[0] == NOT:
-        return expr_contains_sym(expr[1], sym_name)
-
-    # AND, OR, or relation
-    return expr_contains_sym(expr[1], sym_name) or \
-           expr_contains_sym(expr[2], sym_name)
+    for item in expr_items(expr):
+        if item.name == sym_name:
+            return True
+
+    return False
 
 def sc_references_sym(sc, sym_name):
     """
diff --git a/kconfiglib.py b/kconfiglib.py
index cee793e..82edcb6 100644
--- a/kconfiglib.py
+++ b/kconfiglib.py
@@ -4422,6 +4422,30 @@ def expr_str(expr):
                              _REL_TO_STR[expr[0]],
                              expr_str(expr[2]))
 
+def expr_items(expr):
+    """
+    Returns a set() of all items (symbols and choices) that appear in the
+    expression 'expr'.
+    """
+
+    deps = set()
+
+    def rec(subexpr):
+        if not isinstance(subexpr, tuple):
+            # Symbol or choice
+            deps.add(subexpr)
+
+        elif subexpr[0] == NOT:
+            rec(subexpr[1])
+
+        else:
+           # AND, OR, or relation
+           rec(subexpr[1])
+           rec(subexpr[2])
+
+    rec(expr)
+    return deps
+
 def split_expr(expr, op):
     """
     Returns a list containing the top-level AND or OR operands in the
diff --git a/tests/Kexpr_items b/tests/Kexpr_items
new file mode 100644
index 0000000..fb97ace
--- /dev/null
+++ b/tests/Kexpr_items
@@ -0,0 +1,11 @@
+config TEST
+    bool
+    default A && (B || !C && D = "E") || F > G || !!!H
+
+choice CHOICE
+    bool "choice"
+
+config TEST_CHOICE
+    bool "test choice" if A
+
+endchoice
diff --git a/testsuite.py b/testsuite.py
index d976c12..1f1bc32 100644
--- a/testsuite.py
+++ b/testsuite.py
@@ -45,7 +45,7 @@ from kconfiglib import Kconfig, Symbol, Choice, COMMENT, MENU, MenuNode, \
                        BOOL, TRISTATE, HEX, STRING, \
                        TRI_TO_STR, \
                        escape, unescape, \
-                       expr_str, expr_value, split_expr, \
+                       expr_str, expr_value, expr_items, split_expr, \
                        OR, AND, \
                        KconfigSyntaxError
 import difflib
@@ -990,6 +990,25 @@ g
                  "A || B || C")
 
 
+    print("Testing expr_items()")
+
+    c = Kconfig("Kconfiglib/tests/Kexpr_items")
+
+    def verify_expr_items(expr, *sym_names):
+        verify_equal(tuple(sorted(item.name for item in expr_items(expr))),
+                     sym_names)
+
+    verify_expr_items(
+        c.syms["TEST"].defaults[0][0],
+        "A", "B", "C", "D", "E", "F", "G", "H"
+    )
+
+    verify_expr_items(
+        c.syms["TEST_CHOICE"].nodes[0].prompt[1],
+        "A", "CHOICE"
+    )
+
+
     print("Testing split_expr()")
 
     def verify_split(to_split, op, operand_strs):