Add initial implemention for plpgsql ast traversal

src/pgspot/path.py

@@ -0,0 +1,115 @@
+# pylint: disable=fixme
+
+
+class Path:
+    """A path is a sequence of steps that will be executed in a PLpgSQL function."""
+
+    def __init__(self, root, steps=None, stack=None):
+        self.root = root
+        # steps is the list of nodes that have been processed
+        self.steps = steps.copy() if steps else []
+        # stack is a list of nodes that are yet to be processed
+        self.stack = stack.copy() if stack else []
+
+    def copy(self):
+        return Path(self.root, self.steps, self.stack)
+
+    def __str__(self):
+        return " -> ".join([str(step) for step in self.steps])
+
+
+def paths(root):
+    p = Path(root)
+    pathes = []
+    dfs(root, p, pathes)
+    yield p
+
+    while pathes:
+        p = pathes.pop(0)
+        t = p.stack.pop(0)
+        dfs(t, p, pathes)
+        yield p
+
+
+def dfs(node, path, pathes):
+    """traverse tree depth first similar to how it would get executed"""
+    if not node:
+        return
+    if node:
+        match node.type:
+            case "PLpgSQL_function":
+                # This should be top level node and so stack should be empty
+                assert not path.stack
+                path.stack = [node.action] + path.stack
+            case "PLpgSQL_stmt_block":
+                # FIXME: Add support for exception handling
+                path.stack = node.body + path.stack
+            case "PLpgSQL_stmt_if":
+                path.steps.append(node)
+                if node.elsif_list:
+                    for elsif in node.elsif_list:
+                        alt = path.copy()
+                        alt.stack = elsif.stmts + alt.stack
+                        pathes.append(alt)
+                if node.else_body:
+                    alt = path.copy()
+                    alt.stack = node.else_body + alt.stack
+                    pathes.append(alt)
+
+                path.stack = node.then_body + path.stack
+
+            # different types of loops
+            # FIXME: Add support for loop exit
+            case (
+                "PLpgSQL_stmt_loop"
+                | "PLpgSQL_stmt_while"
+                | "PLpgSQL_stmt_forc"
+                | "PLpgSQL_stmt_fori"
+                | "PLpgSQL_stmt_fors"
+                | "PLpgSQL_stmt_dynfors"
+            ):
+                path.stack = node.body + path.stack
+
+            # nodes with no children
+            case (
+                "PLpgSQL_stmt_assert"
+                | "PLpgSQL_stmt_assign"
+                | "PLpgSQL_stmt_call"
+                | "PLpgSQL_stmt_close"
+                | "PLpgSQL_stmt_commit"
+                | "PLpgSQL_stmt_dynexecute"
+                | "PLpgSQL_stmt_execsql"
+                | "PLpgSQL_stmt_fetch"
+                | "PLpgSQL_stmt_getdiag"
+                | "PLpgSQL_stmt_open"
+                | "PLpgSQL_stmt_perform"
+                | "PLpgSQL_stmt_raise"
+                | "PLpgSQL_stmt_rollback"
+            ):
+                path.steps.append(node)
+
+            # nodes not yet implemented
+            case (
+                "PLpgSQL_stmt_case"
+                | "PLpgSQL_stmt_exit"
+                | "PLpgSQL_stmt_forc"
+                | "PLpgSQL_stmt_foreach_a"
+            ):
+                raise Exception(f"Not yet implemented {node.type}")
+
+            # nodes that will end current path
+            case (
+                "PLpgSQL_stmt_return"
+                | "PLpgSQL_stmt_return_next"
+                | "PLpgSQL_stmt_return_query"
+            ):
+                path.steps.append(node)
+                path.stack.clear()
+                return
+
+            case _:
+                raise Exception(f"Unknown node type {node.type}")
+
+    while path.stack:
+        t = path.stack.pop(0)
+        dfs(t, path, pathes)

src/pgspot/plpgsql.py

@@ -4,14 +4,13 @@
 #
 # Disable pylint warnings about class names cause we are trying to match the
 # AST names used by PLpgSQL parser.
-# pylint: disable-msg=C0103
-# pylint: disable-msg=R0903
+# pylint: disable-msg=invalid-name,too-few-public-methods
 
 
 class PLpgSQLNode:
     def __init__(self, raw):
         self.type = list(raw.keys())[0]
-        self.lineno = None
+        self.lineno = ""
         for k, v in raw[self.type].items():
             setattr(self, k, build_node(v))
 
@@ -24,6 +23,24 @@ def __repr__(self):
         return f"{self.type}({fields})"
 
 
+class PLpgSQL_stmt_if(PLpgSQLNode):
+    def __init__(self, raw):
+        self.then_body = None
+        self.elsif_list = None
+        self.else_body = None
+        super().__init__(raw)
+
+
+class PLpgSQL_row(PLpgSQLNode):
+    def __init__(self, raw):
+        # PLpgSQL_row has a fields attribute which is a list of dicts that
+        # don't have the same structure as other node dicts. So we pop it out
+        # and set it as an attribute directly instead of having it handled by
+        # recursion.
+        self.fields = raw["PLpgSQL_row"].pop("fields")
+        super().__init__(raw)
+
+
 class PLpgSQL_var(PLpgSQLNode):
     def __init__(self, raw):
         self.refname = None

tests/plpgsql_path_if_test.py

@@ -0,0 +1,149 @@
+from pglast import parse_plpgsql
+from pgspot.plpgsql import build_node
+from pgspot.path import paths
+
+
+def test_if_minimal_stmt():
+    sql = """
+    CREATE FUNCTION foo(cmd TEXT) RETURNS void AS $$
+    BEGIN
+      IF EXISTS (SELECT FROM pg_stat_activity) THEN
+        EXECUTE cmd || '1';
+      END IF;
+    END
+    $$;
+    """
+    parsed = parse_plpgsql(sql)
+    node = build_node(parsed[0])
+    assert node.type == "PLpgSQL_function"
+
+    pathes = list(paths(node))
+    assert len(pathes) == 1
+
+    assert (
+        str(pathes[0])
+        == "PLpgSQL_stmt_if(3) -> PLpgSQL_stmt_dynexecute(4) -> PLpgSQL_stmt_return()"
+    )
+
+
+def test_if_else():
+    sql = """
+    CREATE FUNCTION foo(cmd TEXT) RETURNS void AS $$
+    BEGIN
+      IF EXISTS (SELECT FROM pg_stat_activity) THEN
+        EXECUTE cmd || '1';
+      ELSIF EXISTS (SELECT FROM pg_stat_activity) THEN
+        EXECUTE cmd || '2';
+      ELSIF EXISTS (SELECT FROM pg_stat_activity) THEN
+        EXECUTE cmd || '3';
+      ELSIF EXISTS (SELECT FROM pg_stat_activity) THEN
+        EXECUTE cmd || '4';
+      ELSE
+        EXECUTE cmd || '5';
+      END IF;
+    END
+    $$;
+    """
+    parsed = parse_plpgsql(sql)
+    node = build_node(parsed[0])
+    assert node.type == "PLpgSQL_function"
+
+    pathes = list(paths(node))
+    assert len(pathes) == 5
+
+    assert (
+        str(pathes[0])
+        == "PLpgSQL_stmt_if(3) -> PLpgSQL_stmt_dynexecute(4) -> PLpgSQL_stmt_return()"
+    )
+    assert (
+        str(pathes[1])
+        == "PLpgSQL_stmt_if(3) -> PLpgSQL_stmt_dynexecute(6) -> PLpgSQL_stmt_return()"
+    )
+    assert (
+        str(pathes[2])
+        == "PLpgSQL_stmt_if(3) -> PLpgSQL_stmt_dynexecute(8) -> PLpgSQL_stmt_return()"
+    )
+    assert (
+        str(pathes[3])
+        == "PLpgSQL_stmt_if(3) -> PLpgSQL_stmt_dynexecute(10) -> PLpgSQL_stmt_return()"
+    )
+    assert (
+        str(pathes[4])
+        == "PLpgSQL_stmt_if(3) -> PLpgSQL_stmt_dynexecute(12) -> PLpgSQL_stmt_return()"
+    )
+
+
+def test_if_stmt():
+    sql = """
+    CREATE FUNCTION foo(cmd TEXT) RETURNS void AS $$
+    BEGIN
+      IF EXISTS (SELECT 1 FROM pg_stat_activity) THEN
+          EXECUTE cmd || '1';
+      ELSE
+          EXECUTE cmd || '2';
+          RETURN 'foo';
+      END IF;
+      IF EXISTS (SELECT 1 FROM pg_stat_activity) THEN
+        EXECUTE cmd;
+      ELSE
+        EXECUTE cmd;
+      END IF;
+    END
+    $$;
+    """
+    parsed = parse_plpgsql(sql)
+    node = build_node(parsed[0])
+    assert node.type == "PLpgSQL_function"
+
+    pathes = list(paths(node))
+    assert len(pathes) == 3
+
+    assert (
+        str(pathes[0])
+        == "PLpgSQL_stmt_if(3) -> PLpgSQL_stmt_dynexecute(4) -> PLpgSQL_stmt_if(9) -> PLpgSQL_stmt_dynexecute(10) -> PLpgSQL_stmt_return()"
+    )
+    assert (
+        str(pathes[1])
+        == "PLpgSQL_stmt_if(3) -> PLpgSQL_stmt_dynexecute(6) -> PLpgSQL_stmt_return(7)"
+    )
+    assert (
+        str(pathes[2])
+        == "PLpgSQL_stmt_if(3) -> PLpgSQL_stmt_dynexecute(4) -> PLpgSQL_stmt_if(9) -> PLpgSQL_stmt_dynexecute(12) -> PLpgSQL_stmt_return()"
+    )
+
+
+def test_nested_if_stmt():
+    sql = """
+    CREATE FUNCTION foo(cmd TEXT) RETURNS void AS $$
+    BEGIN
+      IF EXISTS (SELECT FROM pg_stat_activity) THEN
+        EXECUTE cmd || '1';
+      ELSE
+        IF EXISTS (SELECT FROM pg_stat_activity) THEN
+          EXECUTE cmd || '2';
+        ELSE
+          EXECUTE cmd || '3';
+        END IF;
+      END IF;
+    END
+    $$;
+    """
+    parsed = parse_plpgsql(sql)
+    node = build_node(parsed[0])
+    assert node.type == "PLpgSQL_function"
+
+    pathes = list(paths(node))
+    assert len(pathes) == 3
+
+    assert (
+        str(pathes[0])
+        == "PLpgSQL_stmt_if(3) -> PLpgSQL_stmt_dynexecute(4) -> PLpgSQL_stmt_return()"
+    )
+    assert (
+        str(pathes[1])
+        == "PLpgSQL_stmt_if(3) -> PLpgSQL_stmt_if(6) -> PLpgSQL_stmt_dynexecute(7) -> PLpgSQL_stmt_return()"
+    )
+    assert (
+        str(pathes[2])
+        == "PLpgSQL_stmt_if(3) -> PLpgSQL_stmt_if(6) -> PLpgSQL_stmt_dynexecute(9) -> PLpgSQL_stmt_return()"
+    )