Make jsonschema dependency optional (#3784)

requirements.txt

@@ -9,9 +9,10 @@ srsly>=0.0.5,<1.1.0
 # Third party dependencies
 numpy>=1.15.0
 requests>=2.13.0,<3.0.0
-jsonschema>=2.6.0,<3.1.0
 plac<1.0.0,>=0.9.6
 pathlib==1.0.1; python_version < "3.4"
+# Optional dependencies
+jsonschema>=2.6.0,<3.1.0
 # Development dependencies
 cython>=0.25
 pytest>=4.0.0,<4.1.0

setup.py

@@ -232,7 +232,6 @@ def setup_package():
                 "blis>=0.2.2,<0.3.0",
                 "plac<1.0.0,>=0.9.6",
                 "requests>=2.13.0,<3.0.0",
-                "jsonschema>=2.6.0,<3.1.0",
                 "wasabi>=0.2.0,<1.1.0",
                 "srsly>=0.0.5,<1.1.0",
                 'pathlib==1.0.1; python_version < "3.4"',

spacy/errors.py

@@ -385,6 +385,8 @@ class Errors(object):
     E134 = ("Alias '{alias}' defined for unknown entity '{entity}'.")
     E135 = ("If you meant to replace a built-in component, use `create_pipe`: "
             "`nlp.replace_pipe('{name}', nlp.create_pipe('{name}'))`")
+    E136 = ("This additional feature requires the jsonschema library to be "
+            "installed:\npip install jsonschema")
 
 
 @add_codes

spacy/matcher/matcher.pyx

@@ -48,7 +48,10 @@ cdef class Matcher:
         self._extra_predicates = []
         self.vocab = vocab
         self.mem = Pool()
-        self.validator = get_json_validator(TOKEN_PATTERN_SCHEMA) if validate else None
+        if validate:
+            self.validator = get_json_validator(TOKEN_PATTERN_SCHEMA)
+        else:
+            self.validator = None
 
     def __reduce__(self):
         data = (self.vocab, self._patterns, self._callbacks)

spacy/util.py

@@ -14,8 +14,11 @@ import functools
 import itertools
 import numpy.random
 import srsly
-from jsonschema import Draft4Validator
 
+try:
+    import jsonschema
+except ImportError:
+    jsonschema = None
 
 try:
     import cupy.random
@@ -682,7 +685,9 @@ def get_json_validator(schema):
     # validator that's used (e.g. different draft implementation), without
     # having to change it all across the codebase.
     # TODO: replace with (stable) Draft6Validator, if available
-    return Draft4Validator(schema)
+    if jsonschema is None:
+        raise ValueError(Errors.E136)
+    return jsonschema.Draft4Validator(schema)
 
 
 def validate_schema(schema):