handle nan and infinity values properly; fixes #182

Signed-off-by: Denys Smirnov <[email protected]>

Author: Denys Smirnov

fixtures/issue_182.py

@@ -0,0 +1 @@
+_POS_INF = 1e10000

fixtures/issue_182.py.native

@@ -0,0 +1,29 @@
+{
+   'PY3AST': {
+      'ast_type': "Module",
+      body: [
+         {
+            'ast_type': "Assign",
+            'col_offset': 1,
+            lineno: 1,
+            targets: [
+               {
+                  'ast_type': "Name",
+                  'col_offset': 1,
+                  ctx: "Store",
+                  'end_col_offset': 9,
+                  'end_lineno': 1,
+                  id: "_POS_INF",
+                  lineno: 1,
+               },
+            ],
+            value: {
+               'ast_type': "Num",
+               'col_offset': 12,
+               lineno: 1,
+               'n': "inf",
+            },
+         },
+      ],
+   },
+}

fixtures/issue_182.py.sem.uast

@@ -0,0 +1,49 @@
+{ '@type': "python:Module",
+   '@role': [File, Module],
+   '@pos': { '@type': "uast:Positions",
+   },
+   body: [
+      { '@type': "python:Assign",
+         '@role': [Assignment, Binary, Expression],
+         '@pos': { '@type': "uast:Positions",
+            start: { '@type': "uast:Position",
+               offset: 0,
+               line: 1,
+               col: 1,
+            },
+         },
+         targets: [
+            { '@type': "python:BoxedName",
+               '@role': [Left],
+               'boxed_value': { '@type': "uast:Identifier",
+                  '@pos': { '@type': "uast:Positions",
+                     start: { '@type': "uast:Position",
+                        offset: 0,
+                        line: 1,
+                        col: 1,
+                     },
+                     end: { '@type': "uast:Position",
+                        offset: 8,
+                        line: 1,
+                        col: 9,
+                     },
+                  },
+                  Name: "_POS_INF",
+               },
+               ctx: "Store",
+            },
+         ],
+         value: { '@type': "python:Num",
+            '@token': "inf",
+            '@role': [Expression, Literal, Number, Primitive, Right],
+            '@pos': { '@type': "uast:Positions",
+               start: { '@type': "uast:Position",
+                  offset: 11,
+                  line: 1,
+                  col: 12,
+               },
+            },
+         },
+      },
+   ],
+}

fixtures/issue_182.py.uast

@@ -0,0 +1,47 @@
+{ '@type': "Module",
+   '@role': [File, Module],
+   '@pos': { '@type': "uast:Positions",
+   },
+   body: [
+      { '@type': "Assign",
+         '@role': [Assignment, Binary, Expression],
+         '@pos': { '@type': "uast:Positions",
+            start: { '@type': "uast:Position",
+               offset: 0,
+               line: 1,
+               col: 1,
+            },
+         },
+         targets: [
+            { '@type': "Name",
+               '@token': "_POS_INF",
+               '@role': [Expression, Identifier, Left],
+               '@pos': { '@type': "uast:Positions",
+                  start: { '@type': "uast:Position",
+                     offset: 0,
+                     line: 1,
+                     col: 1,
+                  },
+                  end: { '@type': "uast:Position",
+                     offset: 8,
+                     line: 1,
+                     col: 9,
+                  },
+               },
+               ctx: "Store",
+            },
+         ],
+         value: { '@type': "Num",
+            '@token': "inf",
+            '@role': [Expression, Literal, Number, Primitive, Right],
+            '@pos': { '@type': "uast:Positions",
+               start: { '@type': "uast:Position",
+                  offset: 11,
+                  line: 1,
+                  col: 12,
+               },
+            },
+         },
+      },
+   ],
+}

native/python_package/python_driver/astimprove.py

@@ -4,6 +4,7 @@
 """
 
 import tokenize
+import math
 from codecs import encode
 from copy import deepcopy
 from io import BytesIO
@@ -125,6 +126,9 @@ def visit_Num(self, node: Node) -> Node:
         if isinstance(node["n"], complex):
             node.update({"n": {"real": node["n"].real,
                                "imag": node["n"].imag}})
+        # infinity and nan are not json-serializable
+        elif not math.isfinite(node["n"]):
+            node.update({"n": str(node["n"])})
         return node
 
     def visit_NoneType(self, node: Node) -> Node: