1// Copyright 2013 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// This file implements the visitor that computes the (line, column)-(line-column) range for each function.
6
7package main
8
9import (
10	"bufio"
11	"fmt"
12	"go/ast"
13	"go/build"
14	"go/parser"
15	"go/token"
16	"os"
17	"path/filepath"
18	"text/tabwriter"
19
20	"golang.org/x/tools/cover"
21)
22
23// funcOutput takes two file names as arguments, a coverage profile to read as input and an output
24// file to write ("" means to write to standard output). The function reads the profile and produces
25// as output the coverage data broken down by function, like this:
26//
27//	fmt/format.go:30:	init			100.0%
28//	fmt/format.go:57:	clearflags		100.0%
29//	...
30//	fmt/scan.go:1046:	doScan			100.0%
31//	fmt/scan.go:1075:	advance			96.2%
32//	fmt/scan.go:1119:	doScanf			96.8%
33//	total:		(statements)			91.9%
34
35func funcOutput(profile, outputFile string) error {
36	profiles, err := cover.ParseProfiles(profile)
37	if err != nil {
38		return err
39	}
40
41	var out *bufio.Writer
42	if outputFile == "" {
43		out = bufio.NewWriter(os.Stdout)
44	} else {
45		fd, err := os.Create(outputFile)
46		if err != nil {
47			return err
48		}
49		defer fd.Close()
50		out = bufio.NewWriter(fd)
51	}
52	defer out.Flush()
53
54	tabber := tabwriter.NewWriter(out, 1, 8, 1, '\t', 0)
55	defer tabber.Flush()
56
57	var total, covered int64
58	for _, profile := range profiles {
59		fn := profile.FileName
60		file, err := findFile(fn)
61		if err != nil {
62			return err
63		}
64		funcs, err := findFuncs(file)
65		if err != nil {
66			return err
67		}
68		// Now match up functions and profile blocks.
69		for _, f := range funcs {
70			c, t := f.coverage(profile)
71			fmt.Fprintf(tabber, "%s:%d:\t%s\t%.1f%%\n", fn, f.startLine, f.name, 100.0*float64(c)/float64(t))
72			total += t
73			covered += c
74		}
75	}
76	fmt.Fprintf(tabber, "total:\t(statements)\t%.1f%%\n", 100.0*float64(covered)/float64(total))
77
78	return nil
79}
80
81// findFuncs parses the file and returns a slice of FuncExtent descriptors.
82func findFuncs(name string) ([]*FuncExtent, error) {
83	fset := token.NewFileSet()
84	parsedFile, err := parser.ParseFile(fset, name, nil, 0)
85	if err != nil {
86		return nil, err
87	}
88	visitor := &FuncVisitor{
89		fset:    fset,
90		name:    name,
91		astFile: parsedFile,
92	}
93	ast.Walk(visitor, visitor.astFile)
94	return visitor.funcs, nil
95}
96
97// FuncExtent describes a function's extent in the source by file and position.
98type FuncExtent struct {
99	name      string
100	startLine int
101	startCol  int
102	endLine   int
103	endCol    int
104}
105
106// FuncVisitor implements the visitor that builds the function position list for a file.
107type FuncVisitor struct {
108	fset    *token.FileSet
109	name    string // Name of file.
110	astFile *ast.File
111	funcs   []*FuncExtent
112}
113
114// Visit implements the ast.Visitor interface.
115func (v *FuncVisitor) Visit(node ast.Node) ast.Visitor {
116	switch n := node.(type) {
117	case *ast.FuncDecl:
118		start := v.fset.Position(n.Pos())
119		end := v.fset.Position(n.End())
120		fe := &FuncExtent{
121			name:      n.Name.Name,
122			startLine: start.Line,
123			startCol:  start.Column,
124			endLine:   end.Line,
125			endCol:    end.Column,
126		}
127		v.funcs = append(v.funcs, fe)
128	}
129	return v
130}
131
132// coverage returns the fraction of the statements in the function that were covered, as a numerator and denominator.
133func (f *FuncExtent) coverage(profile *cover.Profile) (num, den int64) {
134	// We could avoid making this n^2 overall by doing a single scan and annotating the functions,
135	// but the sizes of the data structures is never very large and the scan is almost instantaneous.
136	var covered, total int64
137	// The blocks are sorted, so we can stop counting as soon as we reach the end of the relevant block.
138	for _, b := range profile.Blocks {
139		if b.StartLine > f.endLine || (b.StartLine == f.endLine && b.StartCol >= f.endCol) {
140			// Past the end of the function.
141			break
142		}
143		if b.EndLine < f.startLine || (b.EndLine == f.startLine && b.EndCol <= f.startCol) {
144			// Before the beginning of the function
145			continue
146		}
147		total += int64(b.NumStmt)
148		if b.Count > 0 {
149			covered += int64(b.NumStmt)
150		}
151	}
152	if total == 0 {
153		total = 1 // Avoid zero denominator.
154	}
155	return covered, total
156}
157
158// findFile finds the location of the named file in GOROOT, GOPATH etc.
159func findFile(file string) (string, error) {
160	dir, file := filepath.Split(file)
161	pkg, err := build.Import(dir, ".", build.FindOnly)
162	if err != nil {
163		return "", fmt.Errorf("can't find %q: %v", file, err)
164	}
165	return filepath.Join(pkg.Dir, file), nil
166}
167