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Rewrite default template to handle nested ifs, != and env vars in if
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The awk script now performs all processing in the BEGIN block using an
implementation that is capable of handling nested if statements. This fixes
issue #436. Includes are now handled in the same way as the main file which
means that recursive includes and if statements in includes works as
expected. This fixes #406.

All variables are handled in the same way now so it's now possible to use env
variables in if statements. This fixes #488.

Also add support for != in addition to == (fixes #358). Thus it's now
e.g. possible to check if a variable is set (#477) by doing:

{% if yadm.class != ""%}
Class is set to {{ yadm.class }}
{% endif %}

Possible breaking change: An error will be issued if a non-existent yadm or env
variable is referenced in an if statement or in a variable substitution.
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@erijo
erijo committed Oct 27, 2024
1 parent 76ce3de commit 8bc3b6f
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Showing 2 changed files with 169 additions and 76 deletions.
71 changes: 69 additions & 2 deletions test/test_unit_template_default.py
View file
Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
"""Unit tests: template_default"""

import os

FILE_MODE = 0o754
Expand All @@ -12,6 +13,7 @@
LOCAL_USER = "default_Test+@-!^User"
LOCAL_DISTRO = "default_Test+@-!^Distro"
LOCAL_DISTRO_FAMILY = "default_Test+@-!^Family"
ENV_VAR = "default_Test+@-!^Env"
TEMPLATE = f"""
start of template
default class = >{{{{yadm.class}}}}<
Expand All @@ -30,6 +32,9 @@
{{% if yadm.class == "wrongclass1" %}}
wrong class 1
{{% endif %}}
{{% if yadm.class != "wronglcass" %}}
Included section from !=
{{% endif\t\t %}}
{{% if yadm.class == "{LOCAL_CLASS}" %}}
Included section for class = {{{{yadm.class}}}} ({{{{yadm.class}}}} repeated)
Multiple lines
Expand Down Expand Up @@ -97,6 +102,12 @@
{{% if yadm.distro_family == "wrongfamily2" %}}
wrong family 2
{{% endif %}}
{{% if env.VAR == "{ENV_VAR}" %}}
Included section for env.VAR = {{{{env.VAR}}}} ({{{{env.VAR}}}} again)
{{% endif %}}
{{% if env.VAR == "wrongenvvar" %}}
wrong env.VAR
{{% endif %}}
end of template
"""
EXPECTED = f"""
Expand All @@ -111,6 +122,7 @@
classes = >{LOCAL_CLASS2}
{LOCAL_CLASS}<
Included section from else
Included section from !=
Included section for class = {LOCAL_CLASS} ({LOCAL_CLASS} repeated)
Multiple lines
Included section for second class
Expand All @@ -121,6 +133,7 @@
Included section for distro = {LOCAL_DISTRO} ({LOCAL_DISTRO} again)
Included section for distro_family = \
{LOCAL_DISTRO_FAMILY} ({LOCAL_DISTRO_FAMILY} again)
Included section for env.VAR = {ENV_VAR} ({ENV_VAR} again)
end of template
"""

Expand Down Expand Up @@ -154,6 +167,42 @@
basic
"""

TEMPLATE_NESTED_IFS = """\
{% if yadm.user == "me" %}
print1
{% if yadm.user == "me" %}
print2
{% else %}
no print1
{% endif %}
{% else %}
{% if yadm.user == "me" %}
no print2
{% else %}
no print3
{% endif %}
{% endif %}
{% if yadm.user != "me" %}
no print4
{% if yadm.user == "me" %}
no print5
{% else %}
no print6
{% endif %}
{% else %}
{% if yadm.user == "me" %}
print3
{% else %}
no print7
{% endif %}
{% endif %}
"""
EXPECTED_NESTED_IFS = """\
print1
print2
print3
"""


def test_template_default(runner, yadm, tmpdir):
"""Test template_default"""
Expand Down Expand Up @@ -182,7 +231,7 @@ def test_template_default(runner, yadm, tmpdir):
local_distro_family="{LOCAL_DISTRO_FAMILY}"
template_default "{input_file}" "{output_file}"
"""
run = runner(command=["bash"], inp=script)
run = runner(command=["bash"], inp=script, env={"VAR": ENV_VAR})
assert run.success
assert run.err == ""
assert output_file.read() == EXPECTED
Expand Down Expand Up @@ -243,12 +292,30 @@ def test_include(runner, yadm, tmpdir):
assert os.stat(output_file).st_mode == os.stat(input_file).st_mode


def test_nested_ifs(runner, yadm, tmpdir):
"""Test nested if statements"""

input_file = tmpdir.join("input")
input_file.write(TEMPLATE_NESTED_IFS, ensure=True)
output_file = tmpdir.join("output")

script = f"""
YADM_TEST=1 source {yadm}
set_awk
local_user="me"
template_default "{input_file}" "{output_file}"
"""
run = runner(command=["bash"], inp=script)
assert run.success
assert run.err == ""
assert output_file.read() == EXPECTED_NESTED_IFS


def test_env(runner, yadm, tmpdir):
"""Test env"""

input_file = tmpdir.join("input")
input_file.write("{{env.PWD}}", ensure=True)
input_file.chmod(FILE_MODE)
output_file = tmpdir.join("output")

script = f"""
Expand Down
174 changes: 100 additions & 74 deletions yadm
View file
Original file line number Diff line number Diff line change
Expand Up @@ -368,87 +368,113 @@ function template_default() {
# the explicit "space + tab" character class used below is used because not
# all versions of awk seem to support the POSIX character classes [[:blank:]]
read -r -d '' awk_pgm << "EOF"
# built-in default template processor
BEGIN {
blank = "[ ]"
c["class"] = class
c["classes"] = classes
c["arch"] = arch
c["os"] = os
c["hostname"] = host
c["user"] = user
c["distro"] = distro
c["distro_family"] = distro_family
c["source"] = source
ifs = "^{%" blank "*if"
els = "^{%" blank "*else" blank "*%}$"
end = "^{%" blank "*endif" blank "*%}$"
skp = "^{%" blank "*(if|else|endif)"
vld = conditions()
inc_start = "^{%" blank "*include" blank "+\"?"
inc_end = "\"?" blank "*%}$"
inc = inc_start ".+" inc_end
prt = 1
err = 0
}
END { exit err }
{ replace_vars() } # variable replacements
$0 ~ vld, $0 ~ end {
if ($0 ~ vld || $0 ~ end) prt=1;
if ($0 ~ els) prt=0;
if ($0 ~ skp) next;
}
($0 ~ ifs && $0 !~ vld), $0 ~ end {
if ($0 ~ ifs && $0 !~ vld) prt=0;
if ($0 ~ els || $0 ~ end) prt=1;
if ($0 ~ skp) next;
}
{ if (!prt) next }
$0 ~ inc {
file = $0
sub(inc_start, "", file)
sub(inc_end, "", file)
sub(/^[^\/].*$/, source_dir "/&", file)
while ((res = getline <file) > 0) {
replace_vars()
print
}
if (res < 0) {
printf "%s:%d: error: could not read '%s'\n", FILENAME, NR, file | "cat 1>&2"
err = 1
}
close(file)
next
}
{ print }
function replace_vars() {
for (label in c) {
gsub(("{{" blank "*yadm\\." label blank "*}}"), c[label])
yadm["class"] = class
yadm["classes"] = classes
yadm["arch"] = arch
yadm["os"] = os
yadm["hostname"] = host
yadm["user"] = user
yadm["distro"] = distro
yadm["distro_family"] = distro_family
yadm["source"] = source
VARIABLE = "(env|yadm)\\.[a-zA-Z0-9_]+"
current = 0
filename[current] = ARGV[1]
line[current] = 0
level = 0
skip[level] = 0
for (; current >= 0; --current) {
while ((res = getline <filename[current]) > 0) {
++line[current]
if ($0 ~ "^\\{%[ \t]*if[ \t]+" VARIABLE "[ \t]*[!=]=[ \t]*\".*\"[ \t]*%\\}$") {
if (skip[level]) { skip[++level] = 1; continue }
match($0, VARIABLE)
lhs = substr($0, RSTART, RLENGTH)
match($0, /[!=]=/)
op = substr($0, RSTART, RLENGTH)
match($0, /".*"/)
rhs = replace_vars(substr($0, RSTART + 1, RLENGTH - 2))
if (lhs == "yadm.class") {
lhs = "not" rhs
split(classes, cls_array, "\n")
for (idx in cls_array) {
if (rhs == cls_array[idx]) { lhs = rhs; break }
}
}
else {
lhs = replace_vars("{{" lhs "}}")
}
if (op == "==") { skip[++level] = lhs != rhs }
else { skip[++level] = lhs == rhs }
}
else if (/^\{%[ \t]*else[ \t]*%\}$/) {
if (level == 0 || skip[level] < 0) { error("else without matching if") }
skip[level] = skip[level] ? skip[level - 1] : -1
}
else if (/^\{%[ \t]*endif[ \t]*%\}$/) {
if (--level < 0) { error("endif without matching if") }
}
else if (!skip[level]) {
$0 = replace_vars($0)
if (match($0, /^\{%[ \t]*include[ \t]+("[^"]+"|[^"]+)[ \t]*%\}$/)) {
include = $0
sub(/^\{%[ \t]*include[ \t]+"?/, "", include)
sub(/"?[ \t]*%\}$/, "", include)
if (index(include, "/") != 1) {
include = source_dir "/" include
}
filename[++current] = include
line[current] = 0
}
else { print }
}
}
if (res >= 0) { close(filename[current]) }
else if (current == 0) { error("could not read input file") }
else { --current; error("could not read include file '" filename[current + 1] "'") }
}
for (label in ENVIRON) {
gsub(("{{" blank "*env\\." label blank "*}}"), ENVIRON[label])
if (level > 0) {
current = 0
error("unterminated if")
}
exit 0
}
function condition_helper(label, value) {
gsub(/[\\.^$(){}\[\]|*+?]/, "\\\\&", value)
return sprintf("yadm\\.%s" blank "*==" blank "*\"%s\"", label, value)
function error(text) {
printf "%s:%d: error: %s\n",
filename[current], line[current], text > "/dev/stderr"
exit 1
}
function conditions() {
pattern = ifs blank "+("
for (label in c) {
if (label != "class") {
value = c[label]
pattern = sprintf("%s%s|", pattern, condition_helper(label, value));
function replace_vars(input) {
output = ""
while (match(input, "\\{\\{[ \t]*" VARIABLE "[ \t]*\\}\\}")) {
if (RSTART > 1) {
output = output substr(input, 0, RSTART - 1)
}
data = substr(input, RSTART + 2, RLENGTH - 4)
input = substr(input, RSTART + RLENGTH)
gsub(/[ \t]+/, "", data)
split(data, fields, /\./)
if (fields[1] == "env" && fields[2] in ENVIRON) {
output = output ENVIRON[fields[2]]
}
else if (fields[1] == "yadm" && fields[2] in yadm) {
output = output yadm[fields[2]]
}
else {
error("'" data "' is not a known variable")
}
}
split(classes, cls_array, "\n")
for (idx in cls_array) {
value = cls_array[idx]
pattern = sprintf("%s%s|", pattern, condition_helper("class", value));
}
sub(/\|$/, ")" blank "*%}$", pattern)
return pattern
return output input
}
EOF

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