[nfc] Add ability to test code snippets

This demonstrates a flow that can be used to validate that all code
snippets used in the FIRRTL specification can be compiled.  This is
implemented using a simple pandoc filter to extract all FIRRTL code
blocks, write them to the build directory, and then run them all through
firtool.  This may be a little cumbersome as every code example has to be
completely legal FIRRTL.  I.e., this would require a version and circuit
on every code example.  This may not be such a bad thing.

Signed-off-by: Schuyler Eldridge <[email protected]>

Makefile

@@ -5,7 +5,7 @@ IMG_SRCS=$(shell find include/img_src/ -type f -name '*.dot')
 IMG_EPSS=$(IMG_SRCS:include/img_src/%.dot=build/%.eps)
 IMG_PNG=$(IMG_SRCS:include/img_src/%.dot=build/%.png)
 
-.PHONY: all clean format images
+.PHONY: all clean format images test
 .PRECIOUS: build/ build/img/
 
 all: build/spec.pdf build/abi.pdf
@@ -18,6 +18,10 @@ format:
 
 images: $(IMG_EPSS) $(IMG_PNGS)
 
+test: abi.md spec.md | build/
+	pandoc --filter scripts/extract-firrtl-code.py $^ -o /dev/null
+	find -s build/ -type f -name '*.fir' | xargs -n1 firtool -parse-only -o /dev/null
+
 PANDOC_FLAGS=\
 	--pdf-engine=latexmk \
 	--pdf-engine-opt=-logfilewarninglist \

scripts/extract-firrtl-code.py

@@ -0,0 +1,17 @@
+#!/usr/bin/env python3
+
+from pandocfilters import toJSONFilter, CodeBlock
+
+index = 0
+
+def extractFIRRTLCode(key, value, format, meta):
+    global index
+    if key == 'CodeBlock':
+        [[ident, classes, keyvals], code] = value
+        if 'firrtl' in classes:
+            with open(f'build/code-example-{index:03d}.fir', 'w') as f:
+                f.write(code)
+            index += 1
+
+if __name__ == "__main__":
+    toJSONFilter(extractFIRRTLCode)