Generate CallName() and MroFileName() methods.

On Args objects generated for callables.  This is useful for programs
generating .mro files to serve as entry points for running a pipeline,
which will generally need look something like

    @include "pipeline.mro"

    call PIPELINE(
        ...,
    )

These methods allow such a call to be generated by
ast_builder.MakeCallAst, without any additional arguments.

Add bazel rules for generating code with mro2go.  This is a little more
complex than is feasible with a genrule because we need to pick up
transitive mro sources and set MROPATH properly.

Update the generated code comment to use the canonical path to the mro
file, to ensure consistency between different ways of running the tool.

Author: adam-azarchs

cmd/mro2go/BUILD.bazel

@@ -29,8 +29,8 @@ go_test(
         "split_test.go",
     ],
     data = [
-        "split_test.go",
         "split_pipeline_test.go",
+        "split_test.go",
         "struct_pipeline_test.go",
         "testdata/pipeline_stages.mro",
         "testdata/struct_pipeline.mro",

cmd/mro2go/codegen_test.go

@@ -1,5 +1,11 @@
 // Copyright (c) 2020 10X Genomics, Inc. All rights reserved.
 
+//go:generate -command m2g go run . -p main
+//nolint:lll // go:generate's support for splitting a command line is limited.
+//go:generate m2g -input-only -pipeline SUM_SQUARE_PIPELINE -o split_pipeline_test.go testdata/pipeline_stages.mro
+//go:generate m2g -pipeline OUTER -o struct_pipeline_test.go testdata/struct_pipeline.mro
+//go:generate m2g -o split_test.go testdata/pipeline_stages.mro
+
 package main
 
 import (

cmd/mro2go/main.go

@@ -81,6 +81,7 @@ Given the input pipeline.mro:
 	)
 
 A user would run
+
 	$ mro2go -package populate -o stagestructs.go pipeline.mro
 
 to generate stagestructs.go:
@@ -103,6 +104,16 @@ to generate stagestructs.go:
 		MinMapqAttachBc int      `json:"min_mapq_attach_bc"`
 	}
 
+	// CallName returns the name of this stage as defined in the .mro file.
+	func (*PopulateInfoFieldsArgs) CallName() string {
+		return "POPULATE_INFO_FIELDS"
+	}
+
+	// MroFileName returns the name of the .mro file which defines this stage.
+	func (*PopulateInfoFieldsArgs) MroFileName() string {
+		return "pipeline.mro"
+	}
+
 	// A structure to encode and decode outs from the POPULATE_INFO_FIELDS stage.
 	type PopulateInfoFieldsOuts struct {
 		// vcf.gz file
@@ -221,8 +232,7 @@ func main() {
 			"Could not get working directory: %v\n",
 			err)
 	}
-	mroPaths := append([]string{cwd},
-		util.ParseMroPath(os.Getenv("MROPATH"))...)
+	mroPaths := append(util.ParseMroPath(os.Getenv("MROPATH")), cwd)
 	var f *os.File
 	if *stdout {
 		f = os.Stdout
@@ -364,11 +374,15 @@ func MroToGo(dest io.Writer,
 	src []byte, mrofile string, stageNames, mroPaths []string,
 	pkg, outName string, pipeline, onlyIns bool,
 	seenStructs map[string]struct{}) error {
+	canonicalPath, _, err := syntax.IncludeFilePath(mrofile, mroPaths)
+	if err != nil {
+		return err
+	}
 	if ast, err := parseMro(src, mrofile, mroPaths); err != nil {
 		return err
 	} else {
 		return gofmt(dest,
-			makeCallableGoRaw(ast, pkg, mrofile, stageNames,
+			makeCallableGoRaw(ast, pkg, canonicalPath, stageNames,
 				pipeline, onlyIns, seenStructs), outName)
 	}
 }

cmd/mro2go/split_pipeline_test.go

@@ -7,6 +7,7 @@ package main
 import (
 	"bytes"
 	"fmt"
+	"strconv"
 	"strings"
 	"unicode"
 
@@ -191,7 +192,28 @@ func writeStageArgs(buffer *bytes.Buffer, lookup *syntax.TypeLookup,
 	for _, param := range stage.GetInParams().List {
 		writeParam(buffer, lookup, param)
 	}
-	buffer.WriteString("}\n\n")
+	buffer.WriteString(`}
+
+// CallName returns the name of this `)
+	buffer.WriteString(stage.Type())
+	buffer.WriteString(` as defined in the .mro file.
+func (*`)
+	buffer.WriteString(prefix)
+	buffer.WriteString(`Args) CallName() string {
+	return `)
+	buffer.Write(strconv.AppendQuote(make([]byte, 0, 255), stage.GetId()))
+	buffer.WriteString(`
+}
+
+// MroFileName returns the name of the .mro file which defines this `)
+	buffer.WriteString(stage.Type())
+	buffer.WriteString(`.
+func (*`)
+	buffer.WriteString(prefix)
+	buffer.WriteString(`Args) MroFileName() string {
+	return `)
+	buffer.Write(strconv.AppendQuote(make([]byte, 0, 255), stage.File().FileName))
+	buffer.WriteString("\n}\n\n")
 }
 
 func writeStageOuts(buffer *bytes.Buffer, lookup *syntax.TypeLookup,

cmd/mro2go/split_test.go

@@ -4,6 +4,7 @@ go_library(
     name = "ast_builder",
     srcs = [
         "exp.go",
+        "make_call_mro.go",
         "struct.go",
     ],
     importpath = "github.com/martian-lang/martian/martian/syntax/ast_builder",

cmd/mro2go/stage_generator.go

@@ -0,0 +1,29 @@
+package ast_builder
+
+import "github.com/martian-lang/martian/martian/syntax"
+
+// An object, compatible with Bindings (that is, either a string-keyed map or
+// a struct), which can be used to generate a top-level call.
+type CallableArgs interface {
+	// CallName returns the name of this stage as defined in the .mro file.
+	CallName() string
+	// MroFileName returns the name of the .mro file which defines this stage.
+	MroFileName() string
+}
+
+// MakeCallAst generates an ast for a top-level call mro file from an Args
+// object as generated by mro2go.
+func MakeCallAst(input CallableArgs) *syntax.Ast {
+	bindings, err := Bindings(input)
+	if err != nil {
+		panic(err)
+	}
+	return &syntax.Ast{
+		Includes: []*syntax.Include{{Value: input.MroFileName()}},
+		Call: &syntax.CallStm{
+			Id:       input.CallName(),
+			DecId:    input.CallName(),
+			Bindings: bindings,
+		},
+	}
+}

cmd/mro2go/struct_pipeline_test.go

@@ -11,6 +11,7 @@ go_library(
 mro_library(
     name = "sum_squares",
     srcs = ["sum_squares.mro"],
+    visibility = [":__subpackages__"],
 )
 
 mro_test(

martian/syntax/ast_builder/BUILD.bazel

@@ -0,0 +1,28 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("//tools:mro2go.bzl", "mro2go_library")
+
+mro2go_library(
+    name = "pipeline_args",
+    testonly = True,
+    srcs = ["//test/split_test_go:pipeline_stages"],
+    importpath = "github.com/martian-lang/martian/martian/test/pipeline_gen",
+    pipelines = ["SUM_SQUARE_PIPELINE"],
+)
+
+go_library(
+    name = "pipeline_gen",
+    testonly = True,
+    srcs = ["generate_pipeline.go"],
+    embed = [":pipeline_args"],
+    deps = [
+        "//martian/syntax/ast_builder",
+    ],
+)
+
+go_test(
+    name = "pipeline_gen_test",
+    size = "small",
+    srcs = ["generate_pipeline_test.go"],
+    embed = [":pipeline_gen"],
+    gotags = ["bazel"],
+)

martian/syntax/ast_builder/make_call_mro.go

@@ -0,0 +1,16 @@
+//go:build bazel
+// +build bazel
+
+// Package pipeline_gen is used to test the bazel rules for mro2go.
+//
+// It cannot be compiled without bazel.
+package pipeline_gen
+
+import "github.com/martian-lang/martian/martian/syntax/ast_builder"
+
+func GeneratePipeline(values []float64, disableSq bool) string {
+	return ast_builder.MakeCallAst(&SumSquarePipelineArgs{
+		Values:    values,
+		DisableSq: disableSq,
+	}).Format()
+}

martian/test/BUILD.bazel

@@ -0,0 +1,24 @@
+//go:build bazel
+// +build bazel
+
+package pipeline_gen
+
+import "testing"
+
+func TestGeneratePipeline(t *testing.T) {
+	src := GeneratePipeline([]float64{1, 2, 3}, false)
+	const expected = `@include "pipeline_stages.mro"
+
+call SUM_SQUARE_PIPELINE(
+    values     = [
+        1,
+        2,
+        3,
+    ],
+    disable_sq = false,
+)
+`
+	if src != expected {
+		t.Error(src, "!=", expected)
+	}
+}

martian/test/pipeline_gen/BUILD.bazel

@@ -1,4 +1,6 @@
 load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
+load("//tools:mro2go.bzl", "mro2go_codegen")
+load("@bazel_skylib//rules:diff_test.bzl", "diff_test")
 
 go_library(
     name = "sum_squares_lib",
@@ -20,3 +22,18 @@ go_binary(
     embed = [":sum_squares_lib"],
     visibility = ["//visibility:public"],
 )
+
+mro2go_codegen(
+    name = "generate_types",
+    testonly = True,
+    srcs = [
+        "//martian/test:sum_squares",
+    ],
+    package = "main",
+)
+
+diff_test(
+    name = "generate_types_diff_test",
+    file1 = "types.go",
+    file2 = ":generate_types",
+)

martian/test/pipeline_gen/generate_pipeline.go

@@ -1,4 +1,5 @@
-//go:generate mro2go -p main -o types.go ../sum_squares.mro
+//go:generate -command m2g /usr/bin/env MROPATH=.. go run github.com/martian-lang/martian/cmd/mro2go
+//go:generate m2g -p main -o types.go sum_squares.mro
 
 package main
 

martian/test/pipeline_gen/generate_pipeline_test.go

@@ -36,6 +36,8 @@ mro_library(
     name = "pipeline_stages",
     testonly = True,
     srcs = ["pipeline_stages.mro"],
+    mropath = ".",
+    visibility = ["//martian/test/pipeline_gen:__pkg__"],
     deps = [
         "//:sum_squares",
         "//test/split_test_go/stages/report",