small search refactor

.gitignore

@@ -25,15 +25,13 @@ brzaguza.*
 
 .vscode/*
 
-src/engines/yandex/site/*
-src/engines/etools/site/*
-src/engines/swisscows/site/*
-src/engines/metager/site/*
-src/engines/presearch/site/*
+src/engines/*/site/*
+!src/engines/_engines_test
 
 logdump/*.html
 log/*.log
 
 # go generate
 *_stringer.go
-*_enumer.go
+*_enumer.go
+*_searcher.go

generate/searcher/searcher.go

@@ -0,0 +1,319 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/format"
+	"go/token"
+	"go/types"
+	"log"
+	"os"
+	"path"
+	"strings"
+
+	"golang.org/x/tools/go/packages"
+)
+
+var (
+	typeName      = flag.String("type", "", "type name; must be set")
+	output        = flag.String("output", "", "output file name; default srcdir/<type>_searcher.go")
+	trimprefix    = flag.String("trimprefix", "", "trim the `prefix` from the generated constant names")
+	linecomment   = flag.Bool("linecomment", false, "use line comment text as printed text when present")
+	buildTags     = flag.String("tags", "", "comma-separated list of build tags to apply")
+	packageName   = flag.String("packagename", "", "name of the package for generated code; default current package")
+	enginesImport = flag.String("enginesimport", "github.com/tminaorg/brzaguza/src/engines", "source of the engines import, which is prefixed to imports for consts; default github.com/tminaorg/brzaguza/src/engines")
+)
+
+// Usage is a replacement usage function for the flags package.
+func Usage() {
+	fmt.Fprintf(os.Stderr, "Usage of searcher:\n")
+	fmt.Fprintf(os.Stderr, "\tsearcher [flags] -type T [directory]\n")
+	fmt.Fprintf(os.Stderr, "\tsearcher [flags] -type T files... # Must be a single package\n")
+	fmt.Fprintf(os.Stderr, "Flags:\n")
+	flag.PrintDefaults()
+}
+
+func main() {
+	log.SetFlags(0)
+	log.SetPrefix("searcher: ")
+	flag.Usage = Usage
+	flag.Parse()
+	if len(*typeName) == 0 {
+		flag.Usage()
+		os.Exit(2)
+	}
+	/* ----------------------------------
+	//! Should be comma seperated list of type names, currently is only the first type name
+	   ---------------------------------- */
+	types := strings.Split(*typeName, ",")
+	var tags []string
+	if len(*buildTags) > 0 {
+		tags = strings.Split(*buildTags, ",")
+	}
+
+	// We accept either one directory or a list of files. Which do we have?
+	args := flag.Args()
+	if len(args) == 0 {
+		// Default: process whole package in current directory.
+		args = []string{"."}
+	}
+
+	// Parse the package once.
+	var dir string
+	g := Generator{
+		trimPrefix:  *trimprefix,
+		lineComment: *linecomment,
+	}
+
+	if len(args) == 1 && isDirectoryFatal(args[0]) {
+		dir = args[0]
+	} else {
+		if len(tags) != 0 {
+			log.Fatal("-tags option applies only to directories, not when files are specified")
+		}
+		dir = path.Dir(args[0])
+	}
+
+	g.parsePackage(args, tags)
+
+	// Print the header and package clause.
+	g.Printf("// Code generated by \"searcher %s\"; DO NOT EDIT.\n", strings.Join(os.Args[1:], " "))
+	g.Printf("\n")
+	var pkgName string
+	if *packageName == "" {
+		pkgName = g.pkg.name
+	} else {
+		pkgName = *packageName
+	}
+	g.Printf("package %s", pkgName)
+	g.Printf("\n")
+	g.Printf("import \"%s\"\n", *enginesImport) // Used by all methods.
+
+	// Run generate for each type.
+	for _, typeName := range types {
+		g.generate(typeName)
+	}
+
+	// Format the output.
+	src := g.format()
+
+	// Write to file.
+	outputName := *output
+	if outputName == "" {
+		baseName := fmt.Sprintf("%s_searcher.go", types[0])
+		outputName = path.Join(dir, strings.ToLower(baseName))
+	}
+	err := os.WriteFile(outputName, src, 0644)
+	if err != nil {
+		log.Fatalf("writing output: %s", err)
+	}
+}
+
+func (g *Generator) Printf(format string, args ...interface{}) {
+	fmt.Fprintf(&g.buf, format, args...)
+}
+
+// parsePackage analyzes the single package constructed from the patterns and tags.
+// parsePackage exits if there is an error.
+func (g *Generator) parsePackage(patterns []string, tags []string) {
+	cfg := &packages.Config{
+		Mode:       packages.NeedName | packages.NeedTypes | packages.NeedTypesInfo | packages.NeedSyntax,
+		Tests:      false,
+		BuildFlags: []string{fmt.Sprintf("-tags=%s", strings.Join(tags, " "))},
+		Logf:       g.logf,
+	}
+	pkgs, err := packages.Load(cfg, patterns...)
+	if err != nil {
+		log.Fatal(err)
+	}
+	if len(pkgs) != 1 {
+		log.Fatalf("error: %d packages matching %v", len(pkgs), strings.Join(patterns, " "))
+	}
+	g.addPackage(pkgs[0])
+}
+
+// addPackage adds a type checked Package and its syntax files to the generator.
+func (g *Generator) addPackage(pkg *packages.Package) {
+	g.pkg = &Package{
+		name:  pkg.Name,
+		defs:  pkg.TypesInfo.Defs,
+		files: make([]*File, len(pkg.Syntax)),
+	}
+
+	for i, file := range pkg.Syntax {
+		g.pkg.files[i] = &File{
+			file:        file,
+			pkg:         g.pkg,
+			trimPrefix:  g.trimPrefix,
+			lineComment: g.lineComment,
+		}
+	}
+}
+
+// generate produces imports and the NewEngineStarter method for the named type.
+func (g *Generator) generate(typeName string) {
+	values := make(Values, 0, 100)
+	for _, file := range g.pkg.files {
+		// Set the state for this run of the walker.
+		file.typeName = typeName
+		file.values = nil
+		if file.file != nil {
+			ast.Inspect(file.file, file.genDecl)
+			values = append(values, file.values...)
+		}
+	}
+
+	if len(values) == 0 {
+		log.Fatalf("no values defined for type %s", typeName)
+	}
+
+	// Generate code for importing engines
+	for _, v := range values {
+		if validConst(v) {
+			g.Printf("import \"%s/%s\"\n", *enginesImport, strings.ToLower(v.originalName))
+		}
+	}
+
+	// Generate code that will fail if the constants change value.
+	g.Printf("func _() {\n")
+	g.Printf("\t// An \"invalid array index\" compiler error signifies that the constant values have changed.\n")
+	g.Printf("\t// Re-run the searcher command to generate them again.\n")
+	g.Printf("\tvar x [1]struct{}\n")
+	for _, v := range values {
+		origName := v.originalName
+		if *packageName != "" {
+			origName = fmt.Sprintf("%s.%s", g.pkg.name, v.originalName)
+		}
+		g.Printf("\t_ = x[%s - (%s)]\n", origName, v.str)
+	}
+	g.Printf("}\n")
+
+	g.buildOneRun(values, typeName)
+}
+
+// format returns the gofmt-ed contents of the Generator's buffer.
+func (g *Generator) format() []byte {
+	src, err := format.Source(g.buf.Bytes())
+	if err != nil {
+		// Should never happen, but can arise when developing this code.
+		// The user can compile the output to see the error.
+		log.Printf("warning: internal error: invalid Go generated: %s", err)
+		log.Printf("warning: compile the package to analyze the error")
+		return g.buf.Bytes()
+	}
+	return src
+}
+
+func (v *Value) String() string {
+	return v.str
+}
+
+// genDecl processes one declaration clause.
+func (f *File) genDecl(node ast.Node) bool {
+	decl, ok := node.(*ast.GenDecl)
+	if !ok || decl.Tok != token.CONST {
+		// We only care about const declarations.
+		return true
+	}
+	// The name of the type of the constants we are declaring.
+	// Can change if this is a multi-element declaration.
+	typ := ""
+	// Loop over the elements of the declaration. Each element is a ValueSpec:
+	// a list of names possibly followed by a type, possibly followed by values.
+	// If the type and value are both missing, we carry down the type (and value,
+	// but the "go/types" package takes care of that).
+	for _, spec := range decl.Specs {
+		vspec := spec.(*ast.ValueSpec) // Guaranteed to succeed as this is CONST.
+		if vspec.Type == nil && len(vspec.Values) > 0 {
+			// "X = 1". With no type but a value. If the constant is untyped,
+			// skip this vspec and reset the remembered type.
+			typ = ""
+
+			// If this is a simple type conversion, remember the type.
+			// We don't mind if this is actually a call; a qualified call won't
+			// be matched (that will be SelectorExpr, not Ident), and only unusual
+			// situations will result in a function call that appears to be
+			// a type conversion.
+			ce, ok := vspec.Values[0].(*ast.CallExpr)
+			if !ok {
+				continue
+			}
+			id, ok := ce.Fun.(*ast.Ident)
+			if !ok {
+				continue
+			}
+			typ = id.Name
+		}
+		if vspec.Type != nil {
+			// "X T". We have a type. Remember it.
+			ident, ok := vspec.Type.(*ast.Ident)
+			if !ok {
+				continue
+			}
+			typ = ident.Name
+		}
+		if typ != f.typeName {
+			// This is not the type we're looking for.
+			continue
+		}
+		// We now have a list of names (from one line of source code) all being
+		// declared with the desired type.
+		// Grab their names and actual values and store them in f.values.
+		for _, name := range vspec.Names {
+			if name.Name == "_" {
+				continue
+			}
+			// This dance lets the type checker find the values for us. It's a
+			// bit tricky: look up the object declared by the name, find its
+			// types.Const, and extract its value.
+			obj, ok := f.pkg.defs[name]
+			if !ok {
+				log.Fatalf("no value for constant %s", name)
+			}
+			info := obj.Type().Underlying().(*types.Basic).Info()
+			if info&types.IsInteger == 0 {
+				log.Fatalf("can't handle non-integer constant type %s", typ)
+			}
+			value := obj.(*types.Const).Val() // Guaranteed to succeed as this is CONST.
+			if value.Kind() != constant.Int {
+				log.Fatalf("can't happen: constant is not an integer %s", name)
+			}
+			i64, isInt := constant.Int64Val(value)
+			u64, isUint := constant.Uint64Val(value)
+			if !isInt && !isUint {
+				log.Fatalf("internal error: value of %s is not an integer: %s", name, value.String())
+			}
+			if !isInt {
+				u64 = uint64(i64)
+			}
+			v := Value{
+				originalName: name.Name,
+				value:        u64,
+				signed:       info&types.IsUnsigned == 0,
+				str:          value.String(),
+			}
+			if c := vspec.Comment; f.lineComment && c != nil && len(c.List) == 1 {
+				v.name = strings.TrimSpace(c.Text())
+			} else {
+				v.name = strings.TrimPrefix(v.originalName, f.trimPrefix)
+			}
+			f.values = append(f.values, v)
+		}
+	}
+	return false
+}
+
+// buildOneRun generates the variables and NewEngineStarter func for a single run of contiguous values.
+func (g *Generator) buildOneRun(values Values, typeName string) {
+	g.Printf("\n")
+	// The generated code is simple enough to write as a Printf format.
+	g.Printf("\nfunc NewEngineStarter() []EngineSearch {\n\tmm := make([]EngineSearch, %d)", len(values))
+	for _, v := range values {
+		if validConst(v) {
+			g.Printf("\n\tmm[%s.%s] = %s.Search", g.pkg.name, v.name, strings.ToLower(v.name))
+		}
+	}
+	g.Printf("\n\treturn mm\n}")
+}

generate/searcher/structs.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"bytes"
+	"go/ast"
+	"go/types"
+)
+
+// Value represents a declared constant.
+type Value struct {
+	originalName string // The name of the constant.
+	name         string // The name with trimmed prefix.
+	// The value is stored as a bit pattern alone. The boolean tells us
+	// whether to interpret it as an int64 or a uint64; the only place
+	// this matters is when sorting.
+	// Much of the time the str field is all we need; it is printed
+	// by Value.String.
+	value  uint64 // Will be converted to int64 when needed.
+	signed bool   // Whether the constant is a signed type.
+	str    string // The string representation given by the "go/constant" package.
+}
+
+type Values []Value
+
+// Generator holds the state of the analysis. Primarily used to buffer
+// the output for format.Source.
+type Generator struct {
+	buf bytes.Buffer // Accumulated output.
+	pkg *Package     // Package we are scanning.
+
+	trimPrefix  string
+	lineComment bool
+
+	logf func(format string, args ...interface{}) // test logging hook; nil when not testing
+}
+
+// File holds a single parsed file and associated data.
+type File struct {
+	pkg  *Package  // Package to which this file belongs.
+	file *ast.File // Parsed AST.
+	// These fields are reset for each type being generated.
+	typeName string // Name of the constant type.
+	values   Values // Accumulator for constant values of that type.
+
+	trimPrefix  string
+	lineComment bool
+}
+
+type Package struct {
+	name  string
+	defs  map[*ast.Ident]types.Object
+	files []*File
+}