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Aug 10, 2016
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Add grep test data and update readme #327

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251 changes: 251 additions & 0 deletions grep.json
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{
"#": [
"JSON doesn't allow for multi-line strings, so all outputs are presented ",
"here as arrays of strings. It's up to the test generator to join the ",
"lines together with line breaks.",
"",
"The tests are divided into two groups: ",
"* Grepping a single file",
"* Grepping multiple files at once",
"",
"The language track implementing this exercise should",
"ensure that when the tests run, three files are created",
"with the following contents. The file names and their",
"contents are listed in the 'files' section below."
],
"files": [
{
"name": "iliad.txt",
"contents": [
"Achilles sing, O Goddess! Peleus' son;",
"His wrath pernicious, who ten thousand woes",
"Caused to Achaia's host, sent many a soul",
"Illustrious into Ades premature,",
"And Heroes gave (so stood the will of Jove)",
"To dogs and to all ravening fowls a prey,",
"When fierce dispute had separated once",
"The noble Chief Achilles from the son",
"Of Atreus, Agamemnon, King of men."
]
},
{
"name": "midsummer-night.txt",
"contents": [
"I do entreat your grace to pardon me.",
"I know not by what power I am made bold,",
"Nor how it may concern my modesty,",
"In such a presence here to plead my thoughts;",
"But I beseech your grace that I may know",
"The worst that may befall me in this case,",
"If I refuse to wed Demetrius."
]
},
{
"name": "paradise-lost.txt",
"contents": [
"Of Mans First Disobedience, and the Fruit",
"Of that Forbidden Tree, whose mortal tast",
"Brought Death into the World, and all our woe,",
"With loss of Eden, till one greater Man",
"Restore us, and regain the blissful Seat,",
"Sing Heav'nly Muse, that on the secret top",
"Of Oreb, or of Sinai, didst inspire",
"That Shepherd, who first taught the chosen Seed"
]
}
],
"single-file": {
"description": ["Test grepping a single file"],
"cases": [
{
"description": "One file, one match, no flags",
"pattern": "Agamemnon",
"flags": [],
"files": ["iliad.txt"],
"expected": [
"Of Atreus, Agamemnon, King of men."
]
},
{
"description": "One file, several matches, no flags",
"pattern": "may",
"flags": [],
"files": ["midsummer-night.txt"],
"expected": [
"Nor how it may concern my modesty,",
"But I beseech your grace that I may know",
"The worst that may befall me in this case,"
]
},
{
"description": "One file, several matches, print line numbers flag",
"pattern": "may",
"flags": ["-n"],
"files": ["midsummer-night.txt"],
"expected": [
"3:Nor how it may concern my modesty,",
"5:But I beseech your grace that I may know",
"6:The worst that may befall me in this case,"
]
},
{
"description": "One file, one match, print file names flag",
"pattern": "Forbidden",
"flags": ["-l"],
"files": ["paradise-lost.txt"],
"expected": [
"paradise-lost.txt"
]
},
{
"description": "One file, several matches, case-insensitive flag",
"pattern": "ACHILLES",
"flags": ["-i"],
"files": ["iliad.txt"],
"expected": [
"Achilles sing, O Goddess! Peleus' son;",
"The noble Chief Achilles from the son"
]
},
{
"description": "One file, several matches, inverted flag",
"pattern": "Of",
"flags": ["-v"],
"files": ["paradise-lost.txt"],
"expected": [
"Brought Death into the World, and all our woe,",
"With loss of Eden, till one greater Man",
"Restore us, and regain the blissful Seat,",
"Sing Heav'nly Muse, that on the secret top",
"That Shepherd, who first taught the chosen Seed"
]
},
{
"description": "One file, one match, match entire lines flag",
"pattern": "With loss of Eden, till one greater Man",
"flags": ["-x"],
"files": ["paradise-lost.txt"],
"expected": [
"With loss of Eden, till one greater Man"
]
},
{
"description": "One file, one match, multiple flags",
"pattern": "OF ATREUS, Agamemnon, KIng of MEN.",
"flags": ["-n", "-i", "-x"],
"files": ["iliad.txt"],
"expected": [
"9:Of Atreus, Agamemnon, King of men."
]
},
{
"description": "One file, no matches, various flags",
"pattern": "Gandalf",
"flags": ["-n", "-l", "-x", "-i"],
"files": ["iliad.txt"],
"expected": []
}
]
},
"multiple-files": {
"description": ["Test grepping multiples files at once"],
"cases": [
{
"description": "Multiple files, one match, no flags",
"pattern": "Agamemnon",
"flags": [],
"files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
"expected": [
"iliad.txt:Of Atreus, Agamemnon, King of men."
]
},
{
"description": "Multiple files, several matches, no flags",
"pattern": "may",
"flags": [],
"files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
"expected": [
"midsummer-night.txt:Nor how it may concern my modesty,",
"midsummer-night.txt:But I beseech your grace that I may know",
"midsummer-night.txt:The worst that may befall me in this case,"
]
},
{
"description": "Multiple files, several matches, print line numbers flag",
"pattern": "that",
"flags": ["-n"],
"files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
"expected": [
"midsummer-night.txt:5:But I beseech your grace that I may know",
"midsummer-night.txt:6:The worst that may befall me in this case,",
"paradise-lost.txt:2:Of that Forbidden Tree, whose mortal tast",
"paradise-lost.txt:6:Sing Heav'nly Muse, that on the secret top"
]
},
{
"description": "Multiple files, one match, print file names flag",
"pattern": "who",
"flags": ["-l"],
"files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
"expected": [
"iliad.txt",
"paradise-lost.txt"
]
},
{
"description": "Multiple files, several matches, case-insensitive flag",
"pattern": "TO",
"flags": ["-i"],
"files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
"expected": [
"iliad.txt:Caused to Achaia's host, sent many a soul",
"iliad.txt:Illustrious into Ades premature,",
"iliad.txt:And Heroes gave (so stood the will of Jove)",
"iliad.txt:To dogs and to all ravening fowls a prey,",
"midsummer-night.txt:I do entreat your grace to pardon me.",
"midsummer-night.txt:In such a presence here to plead my thoughts;",
"midsummer-night.txt:If I refuse to wed Demetrius.",
"paradise-lost.txt:Brought Death into the World, and all our woe,",
"paradise-lost.txt:Restore us, and regain the blissful Seat,",
"paradise-lost.txt:Sing Heav'nly Muse, that on the secret top"
]
},
{
"description": "Multiple files, several matches, inverted flag",
"pattern": "a",
"flags": ["-v"],
"files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
"expected": [
"iliad.txt:Achilles sing, O Goddess! Peleus' son;",
"iliad.txt:The noble Chief Achilles from the son",
"midsummer-night.txt:If I refuse to wed Demetrius."
]
},
{
"description": "Multiple files, one match, match entire lines flag",
"pattern": "But I beseech your grace that I may know",
"flags": ["-x"],
"files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
"expected": [
"midsummer-night.txt:But I beseech your grace that I may know"
]
},
{
"description": "Multiple files, one match, multiple flags",
"pattern": "WITH LOSS OF EDEN, TILL ONE GREATER MAN",
"flags": ["-n", "-i", "-x"],
"files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
"expected": [
"paradise-lost.txt:4:With loss of Eden, till one greater Man"
]
},
{
"description": "Multiple files, no matches, various flags",
"pattern": "Frodo",
"flags": ["-n", "-l", "-x", "-i"],
"files": ["iliad.txt", "midsummer-night.txt", "paradise-lost.txt"],
"expected": []
}
]
}
}
85 changes: 60 additions & 25 deletions grep.md
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Given a string `filename` and regular expression `pattern`, collect and
return the line numbers and contents of all lines in the file denoted by
`filename` that match `pattern`.

In other words, solutions should open the file described by `filename`
and read each of its lines while keeping track of line numbers (starting at 1).
If a line matches `pattern`, create a pair containing the line's
number and the line itself.
After reading the entire file, return a list of all such pairs sorted
from lowest line number to highest.

The name "grep" comes from the [Unix program](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/grep.html) with the same name.
(In Unix, "grep" was a mnemonic for a useful command to another program [sed](http://www.gnu.org/software/sed/manual/sed.html), whose name means "stream editor".)

The Unix `grep` can be run from the command line and accepts a variety of flags.
Try reproducing some of these in your implementation. For example:
- Accept a pattern and list of files on the command-line, print results
for each file to the console.
- Implement the flags:
- `-l` Print only the names of files that contain at least one matching line.
- `-v` Invert the program -- collect all lines that fail to match the pattern.
- `-x` Only match entire lines, instead of lines that contain a match.
- Support multiple flags at once.
For example, running `grep -l -x "hello" file1.txt file2.txt` should
print the names of files that do not contain the string "hello"
The Unix [`grep`](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/grep.html) command can be used to search for lines in one or more files
that match a user-provided search query (known as the *pattern*).

The `grep` command takes three arguments:

1. The pattern used to match lines in a file.
2. Zero or more flags to customize the matching behavior.
3. One or more files in which to search for matching lines.

Your task is to implement the `grep` function, which should read the contents
of the specified files, find the lines that match the specified pattern
and then output those lines as a single string. Note that the lines should
be output in the order in which they were found, with the first matching line
in the first file being output first.

As an example, suppose there is a file named "input.txt" with the following contents:

<pre>
hello
world
hello again
</pre>

If we were to call `grep "hello" input.txt`, the returned string should be:

<pre>
hello
hello again
</pre>

### Flags

As said earlier, the `grep` command should also support the following flags:

- `-n` Print the line numbers of each matching line.
- `-l` Print only the names of files that contain at least one matching line.
- `-i` Match line using a case-insensitive comparison.
- `-v` Invert the program -- collect all lines that fail to match the pattern.
- `-x` Only match entire lines, instead of lines that contain a match.

If we run `grep -n "hello" input.txt`, the `-n` flag will require the matching
lines to be prefixed with its line number:

<pre>
1:hello
3:hello again
</pre>

And if we run `grep -i "HELLO" input.txt`, we'll do a case-insensitive match,
and the output will be:

<pre>
hello
hello again
</pre>

The `grep` command should support multiple flags at once.

For example, running `grep -l -v "hello" file1.txt file2.txt` should
print the names of files that do not contain the string "hello".