add simple preprocessor

proofs/test.pism

@@ -0,0 +1,69 @@
+# :set syntax=pism
+# :source ../scripts/pism.vim
+constant G_SPEND FixedGenerator
+constant CRH_IVK BlakePersonalization
+constant JUBJUB_FR_CAPACITY BinarySize
+constant NOTE_COMMIT PedersenPersonalization
+
+contract input_spend
+    param secret Fr
+    param ak Point
+    param value U64
+    param is_cool Bool
+    param path Scalar
+{% for n in range(10) %}
+    param path_{{ n }} Scalar
+    param is_right_{{ n }} Bool
+{% endfor %}
+start
+    # Compute P = xG + A
+    witness ak param:ak
+    assert_not_small_order ak
+    fr_as_binary_le secret param:secret
+
+    ec_mul_const public secret G_SPEND
+
+    ec_add public public ak
+    emit_ec public
+
+    # Make some a blake2s hash
+    alloc_binary preimage
+    ec_repr repr_ak ak
+    binary_extend preimage repr_ak
+    static_assert_binary_size preimage 256
+    blake2s ivk preimage CRH_IVK
+    emit_binary ivk
+
+    ############
+    # For loop 10 times
+{% for n in range(10) %}
+    alloc_bit is_right param:is_right_{{ n }}
+    alloc_scalar path param:path_{{ n }}
+{% endfor %}
+    ############
+
+    # Below lines are random garbage
+    # Uncomment them to test
+
+    #binary_clone ivk2 ivk
+    #binary_truncate ivk2 JUBJUB_FR_CAPACITY
+    #u64_as_binary_le value_bits param:value
+    #ec_mul pk_d value_bits public
+
+    #pedersen_hash cm ivk NOTE_COMMIT
+    #ec_get_u cur cm
+    #
+    #alloc_bit is_cool param:is_cool
+    #clone_bit is_cool2 is_cool
+    #binary_push ivk is_cool2
+
+    #alloc_scalar path param:path
+    #conditionally_reverse ul ur cur path is_cool
+
+    #scalar_as_binary ul_bin ul
+    #binary_extend preimage ul_bin
+
+    #scalar_enforce_equal ur ul
+    #emit_scalar ur
+end
+

scripts/preprocess.py

@@ -0,0 +1,18 @@
+import sys
+from jinja2 import Template
+
+def main(argv):
+    if len(argv) != 2:
+        print("error: missing arg", file=sys.stderr)
+        return -1
+
+    input = open(argv[1]).read()
+
+    template = Template(input)
+    print(template.render())
+
+    return 0
+
+if __name__ == "__main__":
+    sys.exit(main(sys.argv))
+