83 lines
2.4 KiB
Makefile
83 lines
2.4 KiB
Makefile
# $NetBSD: varmod-defined.mk,v 1.5 2020/09/12 07:04:51 rillig Exp $
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#
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# Tests for the :D variable modifier, which returns the given string
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# if the variable is defined. It is closely related to the :U modifier.
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DEF= defined
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.undef UNDEF
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# Since DEF is defined, the value of the expression is "value", not
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# "defined".
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#
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.if ${DEF:Dvalue} != "value"
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.error
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.endif
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# Since UNDEF is not defined, the "value" is ignored. Instead of leaving the
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# expression undefined, it is set to "", exactly to allow the expression to
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# be used in .if conditions. In this place, other undefined expressions
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# would generate an error message.
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# XXX: Ideally the error message would be "undefined variable", but as of
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# 2020-08-25 it is "Malformed conditional".
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#
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.if ${UNDEF:Dvalue} != ""
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.error
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.endif
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# The modifier text may contain plain text as well as expressions.
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#
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.if ${DEF:D<${DEF}>} != "<defined>"
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. error
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.endif
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# Special characters that would be interpreted differently can be escaped.
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# These are '}' (the closing character of the expression), ':', '$' and '\'.
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# Any other backslash sequences are preserved.
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#
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# The escaping rules for string literals in conditions are completely
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# different though. There, any character may be escaped using a backslash.
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#
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.if ${DEF:D \} \: \$ \\ \) \n } != " } : \$ \\ \\) \\n "
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. error
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.endif
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# Like in several other places in variable expressions, when
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# ApplyModifier_Defined calls Var_Parse, double dollars lead to a parse
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# error that is silently ignored. This makes all dollar signs disappear,
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# except for the last, which is a well-formed variable expression.
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#
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.if ${DEF:D$$$$$${DEF}} != "defined"
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. error
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.endif
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# Any other text is written without any further escaping. In contrast
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# to the :M modifier, parentheses and braces do not need to be nested.
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# Instead, the :D modifier is implemented sanely by parsing nested
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# expressions as such, without trying any shortcuts. See ApplyModifier_Match
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# for an inferior variant.
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#
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.if ${DEF:D!&((((} != "!&(((("
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. error
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.endif
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# The :D modifier is often used in combination with the :U modifier.
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# It does not matter in which order the :D and :U modifiers appear.
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.if ${UNDEF:Dyes:Uno} != no
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. error
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.endif
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.if ${UNDEF:Uno:Dyes} != no
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. error
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.endif
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.if ${DEF:Dyes:Uno} != yes
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. error
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.endif
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.if ${DEF:Uno:Dyes} != yes
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. error
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.endif
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# TODO: Add more tests for parsing the plain text part, to cover each branch
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# of ApplyModifier_Defined.
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all:
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@:;
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