pandoc_ast: Support multiple versions of pandoc_ast

In order to cope with multiple versions of Pandoc, we need to
support various pandoc_ast versions.  This patch introduces
support for both 0.8 and 0.7, defaulting to the older 0.7.  If
you use Subplot on a system with a much newer pandoc, then switch
to the 0.8 variant to cope.

Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 7085773..b4d473d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,8 +16,14 @@ repository = "https://gitlab.com/larswirzenius/subplot"
 [workspace]
 members = [ "subplotlib", "subplotlib-derive" ]
 
+[features]
+default = ["ast_07"]
+ast_07 = ["pandoc_ast_07"]
+ast_08 = ["pandoc_ast_08"]
+
 [dependencies]
-pandoc_ast = "0.8"
+pandoc_ast_07 = { package = "pandoc_ast", version = "0.7", optional = true }
+pandoc_ast_08 = { package = "pandoc_ast", version = "0.8", optional = true }
 pandoc = "0.8.0"
 structopt = "0.3"
 base64 = "0.13.0"